I want to be raiding at max level (once I get there), but also do some dungeons while leveling, I will be rolling an enh shaman, and horde already has an upper hand with that, but when we ignore racials, which faction is better for raiding (guilds) and low level dungeons?
Or generally said play whatever faction you like more. Both sides have some decent guilds and both sides are doing dungeons while leveling. You'd better chose it according to your affection.
Personally I just love the night elf and their passives are awesome like shadowmeld and the wisp form while being dead. (Also I've read the Lore and the books which has kinda twisted my understanding about the factions hahahha)
So bring whatever you like and you'll still manage to have fun and succeed.