Psychobillybob
In the box I find there really isn't much need to go outside of Sonar at all...(same holds true with Logic)

I find I use third-party plugins far more with Logic than I ever have with Sonar Producer or Splat. Many of Logic's just strike me as indifferent. There's a big price difference between Logic and Sonar of course, which may explain some of it even if Logic is a bit of a "loss leader" to help sell Macs :-)

Like many people I've accumulated quite a number of third-party plugins, and like many people I seem to keep going back to a relatively small number of them.

Waves' Abbey Road consoles, plate reverb, tape and ReelADT are very good. The consoles have a distinctive character like the originals, which were state of the art in their day. Whether they're suitable for everything is a different question of course. The J37, Plate Reverb and ReelADT are among the best of their kind in my opinion.

I use d16’s plugs a lot, not the synths and drum machines but the modulation effects, distortion, sample rate reducer and Sigmund delay. Their flanger in particular, it is very close to the sound and feel of my old Deluxe Electric Mistress but with less noise, a more usable range of controls and it can do far more than the EHX pedal.

BozDigital's plugs are well worth looking at. The +10dB is a nice eq and compressor that's easy to dial in, and the tilt eq is very useful.

Cakewalk's CA-2A is excellent, as is the Concrete Limiter. I just wish the Concrete Limiter came had an AU version like the CA-2A.

Waves Puigtec "Pultec" units are my go-to broad-band eq a lot of the time (the Quad eq or Logic's more basic equivalant I use mostly for surgical things like narrow notching to remove onjectionable resonances), the Nomad Pultec style eqs are OK, and to be honest either will do, it's a matter of personal preference rather than Waves being objectively "better".

Splat comes with one of the most comprehensive plugin suites there is, and none of them are "throwaway" or not usable. All sound somewhere between pretty good to excellent. As far as using Sonar's concerned I mostly use third party stuff for its character rather than because I couldn't manage with just the Cake supplied ones.

As I often say...all that matters is the emotional impact on the listener. I don't see a lot of plug-ins that provide a quantum difference; as most people in the thread have noted these are variations on a theme.
 
There are exceptions. For example, back in the day I was a huge fan of hardware Pultec equalizers. I was very happy when emulations of these started to appear. I'll let others debate whether these sound EXACTLY the same, but I believe at the very least, they fulfill the same function - very smooth, "non-surgical" EQ.
 
I also agree with many people here that Splat has what you need. The Blue Tubes plugs cover a lot of "vintage" applications. I find the Console Emulator very useful and really appreciate that the QuadCurve has four curves. And of course...the CA-2A is excellent.

I agree with what everyone else is saying.  I'll use what's in SPLAT.
It doesn't matter if I use an Abbey Road emulator, I'm not Ken Scott so I won't be able to mix like him anyway.

I will say theoretically "better analog emulation" plug-ins can appear. Perfect analog emulation requires endless computation time (starting with course approximation/sampling original device output it can be continued with emulation of electrical circuit, then finer emulation of concrete elements in it, then the influence of electromagnetic fields inside the device, can be continued with ray tracing fields in the studio... and so on). Computer power increase with time and that can be used in "new version", along with some new mathematical research on topic.
 
But in practice new plug-in appear from marketing. Just because new version should be sold, covering business costs. That has proved to work so far, I guess "the sound" is far from primary reason it works:
* people are looking for "modern GUI". It has even less sense then the color of guitar or LED on CPU cooler, still people are attracted.
* many (I will not write most... someone can see that as a personal attack...) users can not hear the difference between variations of the same FX type. The selection is then based on properties like "expensive", "common standard", "famous", etc. If you have "the best EQ" no one can accuse you "not hearing garbage coming out of freeware/outdated/old version". And no argumentation helps. "Hi-end" world happily selling things which scientifically and practically proved make absolutely no sense. Up to "audiophile quality digital cables".
Anyone can compare threads "what is better, A or B?" with "I uploaded samples processed by A and B, please guess/compare" in this forum. The first type of threads has way more expert answers then the second...
* those how can hear the difference, normally do not (want to) know where it really is. I mean from which extra circuit it comes, may be it is just in small settings or extra FX added. But it is simpler just change between several to find what "works right" here then attempt to understand what is required to make "not working" one working.
Good examples are well known "FX chains". Some of them even "proprietary". Note that they are using a set of other plug-ins, mostly simple one (which you can find looking at binary code of these "presets"). Still they are "different" and have "own character".
 
All that is IMHO from someone who can not distinguish the sound even between completely different analog EQs, so "pff.... why this noob try to judge here?"

I almost never use the included plug-ins.

First, for the most part I prefer the UAD versions of the hardware emulations. I've compared compressors and equalizers and I prefer the UAD plugins - could be any number of reasons, and I haven't thought about it that deeply.

Second, I dislike it when plugins disappear from the marketplace. The biggest upheaval was the whole x86 vs x64 thing, and I'm down to just a couple x86 plugins now for which I wish there were replacements! Sadly Cakewalk has abandoned plugins as much as anyone else, so I try to avoid dependence on all but a few.
 
Third, I dislike plugins that are tied to a specific DAW, regardless of the reason. The Pro-Channel is a really good reason for a plugin to be tied to Sonar, but if I have to choose between a locked and an unlocked plugin the later wins every time.

I don't imagine I'll leave Sonar anytime soon, but I also use Studio One, so I need the flexibility.
 
My random thoughts<G>!

I agree that SPLAT has all you need. I find myself missing Sonar plugins when I use Logic and Studio One. My mixes on Sonar always sound better. I chalk that up to simply knowing the product better. As already stated, the marketing hype on all these emulations are not exactly lies certainly prone to exaggeration. No plugin is an instant "gooderizer" and it will always come down to what works for you. For years i used the old version of "vinyl" as coloring plugin.

I should have mentioned in my original post, one of the reasons I asked this question is because I recently purchased Slate Digital "Everything Bundle Pro", which costs $14.99 a month for 12 months.
It comes with:
E2Deeser – De esser
FG-X   - Mastering plugin includes 3 state of the art mastering processors
Repeater   - 23 authentic delays
S-Gear  - collection of guitar amps, cabinets and effects
VerbSuite Classics   -  digital reverbs
Virtual Buss Compressors  -  analog modeled dynamic processors
Virtual Tape Machines  -   2’ 16 track from NRG Recording and ½” 2 track Howie Weinberg Mastering
VMR ALL Modules w/Monster -   Virtual 500 series rack with swappable modules, putting your whole processing chain in one window
VSC FG-224 Expansion -  digital reverbs


And as I mentioned, I already have most, if not all, of these types of plugins and emulators from either SPlat or Ozone 7 Mastering Suite.   I don't know why I purchased this bundle, I did some side by side comparisons and heard little to no difference, certainly nothing vastly superior to what I already have.  My only excuse is that it was affordable, and it was something I didn't already own. LOL!   Plus the old-style analog-looking interfaces are cool to look at, but difficult to figure out all the knobs' functions.  The Star Trek-like futuristic UI of Ozone 7, also looks cool and the controls are much easier to tell what's what.

Hi, my name is Lee, and I'm a software junkie. 
  "Hi Lee!"

Well, horses for courses, and all that. A lot of people like Slate's stuff, so it's obviously good. I'm put off by the iLok dongle requirement, and I don't like subscriptions unless they're of a certain lifetime variety.
 
It's pretty common to want to collect gear -- be it software or hardware. I don't see a problem with it as long as it's not causing you hardship.

For example tape-emulation:
In my case we have a lot of analog tape machines, like The Studer A80 (Pink Floyd, Alan Parsons ... Millions recorded there album on this machine).
I would never get the idea to master my songs on a reel tape on a Studer A80. There are frequency response falsifications, noise and a lot of other unpleasant things. But this would be really "analog".
And I have never heared a tape emulations that sounds like a real tape machine (I have Slate and UAD tape emulations)

I think Slate's stuff is really good for getting a quick "wow" sound, good presets, the bits and bobs have a great frequency focus for what they do. They sound good.
 
Waves stuff is awesome, I use the SSL channel on all kinds of stuff. I would recommend buying Waves before Slate if you have to choose.
 
I haven't gotten into UAD stuff yet. One my mastering heroes uses them and I want them for that reason, but no monies for it....
 
If you notice you have some insensitivity in your hearing, you may just be happy with Slate, SPLAT, and Ozone, they will do anything you can hear. I mean, there is a measure of "better" for analogue plugins, and if you go with the big names anything you do will make you happy :) I think the bottom line is just getting the demos and see what makes you smile.