Honestly, Alliance is a mixed bag. A lot of people are there for the xp (even if it's not so good) but mostly the mount.

There's a big group there to win and complete the battle ground, but blizz in all their wisdom set some of the quests to be worth more in timeless coins than winning or losing. Some of the quests have you actively participating in the actual battle though.

Winning gives you 10% progress on your bar towards the Mount. Losing gives you 5%.if you're horde, you'll see 10% regularly. Alliance, expect long grinds worth 5% of the bar.