For males, you can pretty much go with the default body, AFAIK. I see far fewer armor models that require an alternative male mod, most usually just offer support for one. Those that do require it tend to be on the fashion-y end.
For females, your recommended choices are: default, UNP (collects a lot of Japanese attention, tends to have more clothed women but not an absolute rule, tends to be 'fashiony'), CBBE (most popular body mod, armor mods for this are more often extremely skimpy but this is not a hard rule.)
I personally would advocate UNP, having tried all three, but that's just me.

