Sorry for the newbie question, but when you are shopping for plugins, what format should you be looking for?  I know they are VST's, but it seems like there are several formats to choose from......for instance, I was looking at one called "Americana Songwriter".......when you purchase it and go to download, there are WAV/ACID, Apple Loops, REX, RMX.  There is also a download for Kontakt 4 and 5.  Which download works in Sonar?  I would have downloaded the Kontakt 5 but there is a disclaimer that says the product does not work with the free kontakt player.
 
Thanks

You are confusing plug-in (and synth) software format with loop sound file format.  VST is the most common of the former, and within that designation is 32-bit and 64-bit.  Several other formats, like AU for Mac, exist.
 
I don't have much knowledge of the latter since I don't play around with loops.  But whatever sample-playback instrument you have will dictate which file types with which it will be compatible.  Check your sample-player documentation for details.  Many sample players can support multiple formats.  Which one is best?  Somebody else will have to make that recommendation.

Samples and loops usually take one of the following formats

NKI - which is Kontakt Format
WAV - can be used by most sample players
AIFF - also can be used by many sample players
SFZ - is soundfont format, used by many players
REX - used by Reason Samplers...

And there are others...

WAV and AIFF are pretty universal, and can be imported into most DAW's, even in
the absence of a sample player...

Here is an in depth guide...

https://en.wikipedia.org/wiki/Audio_file_format

Just an additional note. Anything can be made into a Kontakt 'instrument' or for that matter a VST. I could record curses and map them to keys. When I was starting I got a couple country type 'instruments' cause I'm kind of a hick. The stupid banjo, mandolin, etc... didn't play a middle C note when I hit middle C, instead they start playing whatever loop had been mapped to that key which was something like a 199 bpm G chord. I could have used a curse VST at that moment. So wasted 20 bucks.
 
So if you want an instrument be sure to get a real one and not some crappy loop set masquerading as an instrument. Right now VST4Free is good for free VSTs. Bedroom Producers Blog has nice info on vsts and sfzs. Get free Sforzando and google free sfzs. There are really nice ones out there.

Thanks for all the info......very helpful!

Regarding vst plugin, try not to buy 32bit cause they are being phased out. Steinberg the creater of vst had just recently annouced they are no longer supporting 32bit vst.

Many folks in this forum including myself no longer use them.

A caveat to that would be VSTs that are "only" 32bit. I tend to gravitate to VSTs with both 32 and 64 bit formats for a couple reasons. First, it demonstrates customer support in a subtle way that differentiates many. Second, I actually use a 32-bit wav editor that can use them (because it has features that SONAR may never have). I do, however, use only 64 bit VSTs is 64-bit SONAR.

Before we drift too far off-topic and just confuse the OP, please refer to the original post, in which "VST" was inadvertently used in error. The actual question is about loop formats, not VSTs.
 
I do not use loops and am therefore no expert, but I believe SONAR can handle all of those formats. The Kontakt 4/5 version would be my first choice. But if you don't have the full version of Kontakt, then either ACIDized waves or REX files would work fine, if a little less convenient than a Kontakt library.
 
 

similar thread http://forum.cakewalk.com/FindPost/3116417