Love uniforms, typically of the militaristic or fantastical/sci-fi nature, but other ones can be just as lovely. It's definitely a favorite fetish of mine.

For me, it has more to with the fact that uniforms, at least in my eye, frame a man's figure and brings out his shoulders, arms, and torso a lot more, almost like a tuxedo and that just enhances his features all around. Uniforms are a bit more stiff, rigid, and the male body is a bit straighter than a woman's, whose lingerie curves to her body to visually enhance her definitive characteristics, like breasts, hips, legs, etc. So, for me, men in uniform is eyecandy because it just enhances the male body than a pair of baggy pants in very much the same way a bikini clad woman may do more for a man than her in a regular t shirt and jeans.

Not to say there isn't sexy underwear for men and that uniforms for women don't contour to their bodies too, because they do, but I just love it that much more for men.

Of course, not to say a man or a woman can't look great outside of uniform, just explaining why I particularly like them. Also, it adds a streak of authority, which is hot too. That and I find them fashionable too.