Imperials base stats are the best hands down for a battlemage this time around. They get +10 to restoration, and +5 to destruction, heavy armor, and one handed. Perfect starting stats for a battlemage.
Skill bonuses mean nothing in this game. What really means something is a starting racial ATTRIBUTE, such as the Argonian's ability to breathe underwater, the Khajiit's bonus damage to unarmed, etc.
It's actually a better strategy to pick a race that has NO skill bonus in what you want. That way your chosen skills (the ones you intend to use) will level up faster, which will make your character level up faster as well. And whenever you feel like increasing a skill you don't often use, who knows, maybe it'll already start with a +10 bonus, due to the race you picked at the start of the game.
So in this case (the battlemage), I would HIGHLY consider picking the High Elves, as they start with +50 magicka. You get a nice magicka boost, enabling you to spend some good level ups in Health or Stamina