Aesthetically, blood elf for female and tauren for male. Male blood elves are a bit feminine, too skinny for plate and have quite terrible running animation. Tauren, on the other hand, are fucking alpha males.
Technically, tauren are a bit large and will occasionally get stuck somewhere because of that, but only during questing. Once you get to farming, the probability of getting stuck somewhere because of the size is negligible. On the bright side, they have 0.5 sec herb gather cast time, which is a minor, but still advantage.