the word "best" is subjective.
This is my perspective of it:
If you want.
Everything working + stock performance/batterylife > Maclite
performance + good battery life + decent theme support > CM7
awesome customization/looks + decent battery life/performance > MIUI
CM7 features w/o themes + unique UI > lewa ui2.0 30.03 version
CM7 features + better themes and ui + good gaming performance > mokee (my current rom )
there's still an old favorite - andro-id RC2. which was one of the best custom rom before CM7 and MIUI came along....
flash whichever you think you might like or everything and decide for yourself.... have a blast!
Generally that's the overview, but getting down to further details, I'm looking for one that doesnt randomly reboot often, has no incoming call volume issues, no unknown network operators and whatever little bugs that could hinder daily use.
i dont bother about performance esp in gaming, after all, if i really wanted a gaming device i wouldve gotten an s2 or One X. so anyone can suggest what's good?
my only weakness is im a sucker for themes thats why i tend to favour MIUI despite most of the roms still with bugs here and there. also MIUI's toggles and customization are really handy. but, if there is a rom stable enough, i would give this up for it.