Actually may be it is only me but overall female characters look better in the games.
It's the female's lot in games to look pretty.
Personally I prefer the male wizard and demon hunter, primarily because I don't like the female voice actors for these classes. In two years I haven't spent more than ten seconds or so with any of the others, so I really don't know how the voices compare between sexes, nor am I all that certain how the feminine counterparts actually look like...
I hope the fem witch doctor isn't as spazzy/parkinson-like as the male. I think I would enjoy witch doctoring considering their skill set (summons, magic, which was what was cool with D2 necromancers, which WDs resemble strongly), however the art style for WD armors and weapons simply SUCK. I don't enjoy looking at a walking garbage pile as I play...
Templar I prefer the female, for both voice and the physical appearance. The male's voice sounds so utterly...boring. Detached. He speaks like a traffic warden or something like that.
When it comes to wizard versus demon hunters... I dunno. I actually prefer wizards' play mechanics and offensive skillset over that of the demon hunter. SO OFTEN I am just all out of hatred with my demon hunter, and the hatred generator skills all do pitiful damage. I also feel like my AoE suck as demon hunter; single-target DPS feels strong but I don't quite know what to pick for AoE (and there's so many situations that require AoE in Diablo games.
Strafe is visually unimpressive, it just doesn't pack much punch really, there's elemental arrow - ice, but the arrows only split down-stream; if a wall of enemies rather than a column come at me, it's not much use. Multishot is so DAMN COSTLY. A couple bursts and I'm all out of hatred.
Wizard regens resource MUCH faster, and chain lightning is a great AoE, plus it regens resource. Most other skills also have inherent AoE effects or runes that grant them. Plus, very high damage. It's the defensive skills that are boring/lackluster IMO...