ok the long and the short of it (this is based on what i know only)
the short - you don't really have a choice between 5sp auto and CVT, that is determined by what car you get
the long - early model V35 sedans have only manual or CVT, no regular 5sp that i'm aware of. this means that if you wnt a series 1 sedan (2001 to 2004) then you must get CVT. if you want a series 2 car (late 2004 onwards) then you only get 5sp auto
and of course if you want a coupe then 5sp auto was the ONLY choice again
so choose what year you want and the rest will be determined by that
what to look out for?
do a search i have written this many times in other threads, essentially look for the car with the MOST features you can get, make sure it has leather/suede, bose upgrade, steering wheel buttons, auto-off headlights, dual climate control, TV/nav, etc