What is the best JSF platform?

I work with richfaces and primefaces , both is nice , but I think primefaces better because of it easier in configuration , has useful component ,ajax is simple and its primefaces showcase is simple

Here's my opinion: Richfaces is definitely more mature and possibly you may get developers who are experts in.
Primefaces has more components but lack combobox available in Richfaces.
Richfaces does not have a bunch of common components like the "star rating" component, captcha component and password strength.
Primefaces is easier to skin since it is based on themeroller.
It also has more themes than that is available in Richfaces.
Primefaces is tiny and can be implemented in the code easily - not too many dependencies.
Richfaces does not support JSF 2.0 till now (Nov 2010) - Primefaces has a stable release that supports JSF 2.0 Richfaces component growth is pretty much absent...
No new components added in the last few years.
The component library remains stale.
But, have you thought about using GWT?? GWT is a client-side framework, it generates JavaScript from Java.
Your architecture would be a pure client-server, which means: Best to use coarse-grained services All objects that travel to the client side should be fully serializable (it means there's no lazy load, or OpenSessionInView pattern) Since GWT 2.0 you can design your gui using xhtml, which is much easier in regards to styling & structuring HTML GWT tends to favour good architecture, if you mess it up it will be bad to refactor Perfect History (browser back button, bookmarkable urls) support is hard, you probably have to roll your own, although it's easy to hack something right up front.
My previous experience is GWT and JSF and Primefaces.
regards

Long time not use jsf but I recommend PrimeFaces for you it is leading in support of new versions of jsf it was the first to support jsf 2.0 and 2.1, and have multiable component with ajax support, Rich faces also have good support for Ajax and you can use jboos tools with eclipse as IDE it is supporting GUI tools for Rich Faces, ICE Faces as my old knowlage using its own implementation not use the same APIs of JSF

It depend on what you want to implement. If you are using jsf2.0, I recommend to use Primefaces for lazy loading,  otherways Richface is more flexible. I use both Richface and Primefaces  in the same project. 

Richfaces (http://www.jboss.org/richfaces) is JBoss JSF component framework.

Icefaces (http://www.icesoft.org) is Icesoft powerful Rich Internet application framework.

PrimeFaces (http://primefaces.org/) is Prime Technology Ultimate JSF Component Suite.

PrimeFaces is the best because they implements the standard of JSF2.0, but they release every week and if your pages contain jquery it will create conflicts and Javascript error in web console.

To me, it's primefaces. it's the most complete library JSF and better integrated with JSF2.0.The best because, is the best in:- Components available- Documentation (the showcase is realy complete)- Easy to start... And since JSF2.2 (html5 uses and responsive devlopment), we can mention BootStrap library ...I hope it help