I have rebug and Kmeaw installed on two different systems... pretty much solely use the kmeaw PS3 (slim). Did have a prob with the phat rebug on one occasion (rsod), which was pretty much my own fault. I'd go for rebug, just because its still being supported.
3.55 kmeaw as I fear bricking my ps3. Its pretty simple and runs everything quite well. What advantages would the other CFW have? Would they too be hard for a newb to use?
i'm new on the ps3 world, and i need some "lights", don't we have anything yet to break the fw 4.21? i saw something about firm 4.21 was nuked on youtube last week about it, but i didn't see in any forum news about it.