The only real shaman is the tauren. Period.
Male orc imo. The huge shoulders and their animations do it for me.
Although, it may be frowned upon by Blizzard you can always change the appearance of you character to any race with a Model Changer. However, it will not change the way people see your character. I'll be rolling personally a Male Tauren since I want to tank and want to portray an imposing presence.
Female troll
It just seems fitting that a female troll would be a shaman healer to me. It's a good looking class for Male trolls too.
After all these posts I am thinking about switching from Female Orc to Male Tauren.
Male Orc just isn't for me if it has the broken back. I don't understand why is it like that when in cinematics every Male Orc has a straight posture. (from what I've seen at least)
And as for Orc Female, I don't know. I have always played Male characters and the voice might just make me regret my choice.
Tauren male on the other hand has the intimidation when you see one. Big ass shield!
I like Male Orcs for Shamans, but Male Trolls are cool too. I don't like Taurens as anything except Druids (probably because they are the only choice lol). Taurens are just too slow and clunky for me. I feel like an old person when I play as one. It's like the feeling you get when you try to run through waist-deep water, ya know?
Female orcs then female trolls,
I like their posture and casting animations