I never thought about it, but I guess my choice will be
cop/military, cuz it is the most strict stuff, fifth essence of the uniform I'd say
I find the contrast between girls sexuality and overstrict unhumorous outfit to be very exciting! like a sexy chick is covered inside that severe envelope... but her seductiveness is bursting through! this is really cool!
and in opposite way, I do not like cheerleader/schoolgirl style at all. It does look to infantile and flashy at the same time (kinda cheap slut effect).
Can't stand anything linked with marriage, so brides are also not my cup of tea.
In general, it is better when uniform is as realistic as possible. For example there are a lot of "porno nurses" outfits, that you will never meet in a real hospital. As well as porno-cops, with ultra mini skirts and almost nude boobies, like it was made especially for a porno movie. Genuine uniform is much more sexy to my mind (when I know that in the next frame she will undress herself
)