Seems like alliance is slightly lower in numbers compared to horde. So if you roll alliance you'll have shorter BG queues but still thousands of people to play with.
If you're already on Alliance side and hit 60, consider helping fellow alliance players hit 60 as well. Many people will by default never hit 60, this number will fall a lot further down because of ganking. Help out people in your faction if you can
Seems like it is currently a bit harder to level as alliance compared to horde, but alliance is far better off once they do hit 60.. And the horde gankers are just making it worse for themselves in the long run