Oh, the old debate... After a quick glance at a few of the replies so far, I have to say I agree with those who say neither. Armor bikini is right out, makes no sense and it's, well, demeaning (and I'm saying that as a straight guy...), but the walking tank is inappropriate for an adventurer too. The "tank" look MAY happen later in the game, with heavily enchanted armor that weighs much less than it should by the looks of it, but should still be put together in such a way as to not hamper movement too much.
Wrote
a post about this once, though that was after the issue stared me in the face in an MMO (one of the few I tried, didn't last long of course) and I approached it mainly from that perspective, the general idea applies anywhere.
I say that for the basic armor you should take real armor designs that fit with the game's world design, maybe make a few small changes to improve that fit even more, and leave it at that, without unnecessary differences between male and female models. So same armor for both sexes, just with the necessary alterations for the obvious physical differences, but largely trying to make said differences less noticeable (and definitely keeping it looking useful, as in not deflecting blows to face, as somebody pointed out).
And, of course, again as others said, at least the regular adventuring armor types should stick to light and at most medium armor (but please, something that makes sense, no "studded leather" (about as protective as plain leather, only much heavier) or "ring" (anything pointy goes right through), and "chainmail" is a misnomer, it's just mail...). Later, when it comes to enchanted armor, as enchantments lower weight you can go to heavy and/or start embellishing it to make it also look cool while still remaining functional.
Bottom line, armor should protect your body without sacrificing too much of your speed and mobility, so make it look like it does just that. There's a real dearth of reasonable armor in games (or fantasy art for that matter).
