I was going to say starwarshelmets.com buuuuuut Jez beat me to it. There is alot of info repeated over and over on this and many many sites. An index would be great, however redundant as hell I actually chose my first set of armor after surfing for several weeks. Starwarshelmets.com had pics of everyones armor.
It basically comes down to a small grid
Skinny-Medium Build and 5'8" - 6'0 = AP, TE2, TM
Medium build and 6' to 6'10"=FX
Chubby 5'8" to 6' RT-MOD, FX
Fat? Imperial officer uniform or TK4510 T-shirt.....which is where I am at
Of course there are exceptions... Shims baby, shims!!
FX totally innacurate ABS
AP pretty accurate and ABS
TE2 Styrene and very Accurate
TM ABS and glossy HIPS most accurate
There is a whole host of other makes and types but they come from these armors in recast form of some kind...
Thats about all I can think of. What'd I miss, cause I know I missed something