4.65.2 D-REX, It has so many options and almost every app built into it, You dont need psnpatch or even multiman to startup games or even delete syscals.
Depends on if you are on CEX or DEX, if you are on CEX i would go to rebug 4.70 rex, if you are on dex i would go to PS3ITA 4.65( which is the one i prefer) or rebug 4.70 d-rex
Best Firmware is OFW 4.70. No Bugs and very low risk of getting banned :-) :-)
But im currently on PSita 4.65 DEX and im really happy with. By the way Rebug is great to. U can't do with that anything wrong :-) :-)