One thing that is often overlooked is how are we defining "sounds better" when comparing instruments?
 
How is a fair comparison to be made?  The bottom line is the perception and intended use by the end user.

Are we judging the samplers and synths in the same way?  Based on what? Sample quality, factory presets, sound source (sample playback, analog modeling, physical modeling), the sound architecture, the available expansion packs, the ease or depth of programmability?

Some folks just want preset sounds to quickly set up an arrangement.  That's fine.  Others may want to develop their own sounds and presets.  So they want more capability under the hood.   Different styles of music have varying sonic expectations.  I doubt there is one instrument that meets everybody's needs.  Just look at the sheer number of the available plugins and libraries.  None of them sound inherently bad.  But there are good and bad patches everywhere.
 
That said, I like Dimension Pro, but I wouldn't buy Platinum just for that.  I don't think that Dimension was ever intended to compete with the other commercial sampler libraries, but was intended to provide a starting point for creative sound design.  It came with a library as a bonus.  It is unique.  It's a synthesizer that uses samples for a sound source.

But the synth technology that RGC audio (Rene Ceballos) developed, which was bought by Cakewalk, is a good one. It underlies all of the major Cakewalk synths - Triangle, Square, Pentagon, Dimension Pro, Rapture, Z3TA+ 2, etc.  The original RGC audio z3ta+ is still considered great by many.  I think Rene was possibly way ahead of the current pack of synth developers.
 

Sanderxpander
In a way, but the question is is it worth to spring for Platinum or better to save money and go third party.

I didn't hear any mention of 3rd party plug ins in the OP or his following posts.
not sure how we keep getting side tracked on that (I include myself as well / my previous posts)
He just wants to know if its worth it to spring for platinum vs. professional. and said he heard a review someone said the virtual instruments sounded dated.
 
So I guess the question is, is it worth it ?
 

abacab
One thing that is often overlooked is how are we defining "sounds better" when comparing instruments?
 
How is a fair comparison to be made?  The bottom line is the perception and intended use by the end user. 

 
Yup. I'll give you an example that is by no means typical, but it demonstrates the "slippery slope" of simply assuming that something is going to sound better.
 
I'm a huge Kontakt fan, which is probably not surprising since I wrote the manual for version 1. It's supported by a number of excellent libraries, and the scripting capabilities are extremely sophisticated. There's nothing quite like Action Strings, for example. Also, NI has produced superb content; they didn't just rely on third parties to do the job.
 
However it does take time to load some of the bigger libraries and as I've mentioned in various articles, I often use simple instruments as placeholders while creating a song, then substitute while mixing.
 
In one song the choir was TTS-1 and the strings were SI-Strings. When it was time to mix, I could not find anything in Kontakt that fit the song better. The latter is important, because if you listened to the libraries in isolation, the Kontakt ones sounded "better." But they didn't sound "better" when mixed in with the rest of the tracks. Why? I don't know, but the TTS-1 choir and SI-Strings ended up in the final mix. 
 
This is why I find generalizations pretty much meaningless. The only real answer is to know whatever tools you have, and always keep an open mind. Cost and sophistication may matter...or they may not. As the late John Simonton said, "A real musician can make music with two spoons and a glass."
 

Very good point Graig. I use a Sound Canvas to start things off often. Its an SC 8850. That is old and dated however there some sounds on it that are impossible to find elsewhere. As you say it may not be the sound itself but how it integrates in the song. 
 
In the end of all this, don't we all actually agree having more sounds at ones disposal is better than having a limited set? With Platinum one is given a good start on building a good sound set.
 
 

I guess I did a lackluster job of explaining "worth" and "value" versus "speed" and "simplicity"  I find value in the complete package of Platinum.  Can I go elsewhere sure?  I'm like Craig, I like the Native stuff just fine but when I'm on a roll, I want to move quickly and keep the flow going.  I could probably buy the Artist Version and do everything I want to do. 
 
But lets look at value
Artist $105                Pro:  $209         Platinum:     $499
 
If I have to buy Artist every three or for years, I will pay 300 to 400 dollars... it just depends on updates.
Pro, if I update twice, there's over $400 dollars.
 
Do I find value in the lifetime updates?  I sure do.  A windows update could break sonar.  Access to the update that fixes the functionality--- Priceless.
 
The extra goodies? It may be a big fat question that only your own soul will answer.  Upgrade pricing helps some.  Starting at the bottom of the rung and working your way up financially may also be beneficial.  I didn't start of Pro, I started with Music Creator #2 and tinkered until I decided if I wanted to take the next step.  My next step was Cakewalk Sonar X1 pro... you don't have to dive in to the deep end, take it slow... learn along the way.

bigt1
 
But lets look at value
Artist $105                Pro:  $209         Platinum:     $499
 
If I have to buy Artist every three or for years, I will pay 300 to 400 dollars... it just depends on updates.
Pro, if I update twice, there's over $400 dollars.
 
Do I find value in the lifetime updates?  I sure do.  A windows update could break sonar.  Access to the update that fixes the functionality--- Priceless.

 
Yup!

Value. That's really the bottom line for the sake of this discussion in 2016.  Lifetime updates for Platinum until Dec 31st.
 
If we were having to answer the question about value after Dec 31st, it would probably be in favor of Sonar Professional, based on the OP's stated needs.
 
I feel that the investment in Platinum w/lifetime updates was a no-brainer for me.  I was comfortable with Sonar X3 Producer and would have been OK with sitting on that.  But I already have a couple of other expensive software packages that I no longer qualify for upgrade pricing with, that Microsoft broke with Windows 10.
 
I like knowing that my DAW will always be compatible, regardless of whatever Microsoft does to Windows.  Or possibly even Mac, if it comes to that.  Without spending another buck to buy a new version.  Done.

This thread has been very helpful. Thanks to everyone for your comments and advice.