no such thing as most 'best' rom. Do you like themes/throms, most stable, good/ better performance or?
Throms- Putu 2.2, Monster 5,4,3,1,Admiral Beast (som others too there are also themes to flash on these roms, such as paris's latest ics theme or monster.)
Most stable- Stock,(i'd pick boraichee's deodexed stock rom. stable, fast interface)Stock++,deodexed, ext4, themes, INIT.D AND LOCAL.RC.( some more..), yet again, admiral beast.
Performance wise - Stock++, tweak that shit. Overclock to 850mhz or 900mhz to see which is your phones sweet spot.
BETA Performance Roms. (Beta means there are still some bugs yet to be squashed - I.e fix for a camera or signal bar.)
CM7, Miui. Miui is cool but fees a little bit more buggy than cm7 ( i get some lags)
Cm7 - Has great amount of themes al over the internet/xda. If you dont mind broken GPS, Camera ( download fast burst camera for a temp fix.)
Try cm7.
So as a bugless rom.. Admira beast or stock deodexed.
Try them