Nords and Orcs for me.
Orcs are just plain ol' badass. As far as warrior combat goes, orcs reign supreme. Their racial ability is so awesome and powerful that they're the only race to not get a lesser racial power to compensate. Ignore the Nord waving around the sword nearly as tall as he is, and fear the sword and board orc in custom smithed heavy armor. And don't make any 'orcs got no brains' jokes around the library at the College of Winterhold. FYI.
On the other hand, Nords are also cool and were my favorite race in Oblivion. They fit extremely well into the Skyrim setting (duh) and provide a much more welcoming atmosphere in the cities. Plus, the main quest is very much tied into Nord cultural beliefs and mythology, so it helps immersion to be a Nord. Plus one of the most annoying elemental damage types that magic-using enemies (and some dragons) love to dish out is Frost damage, and Nords get a very welcome resistance to this type. Also, playing a Nord mage is fun, just to play with expectations.