I didn't like Trisfal too much. too many mobs and too many undead mobs which are immune to various things. Belf area is fast as hell to get to 20 in though, but I don't think that is it. It's basically the emo look, erp fashion of my lame server and also the fuckin OP racial for pvp. It is actually a nice racial for pve as well, since its like a free mana pot.
And the Dranei area is also fast and has got good early quest rewards, but its still rather low population wise. Out of the ally characters, I only really move the dwarves/gnomes to elwynn since their starter area is too big and quests too spread apart, a la Barrens. But the only real great starter areas are elwynn/westfall and the Dranei area. Night elves second area, Darkshore, is actually a pain in the ass. Then you have Ashenvale next, where Astranaar has Horde in it more often than Alliance.
I think what hurts Dranei is what also hurts the NE area, that Alliance are never in Darnassus or Exador and most of your sides population is on the other continent. And you don't have a nice easy zepp ride to get there, you have to do an hour long corpse run.
Basically its the pretty look, the fast starter area, the pretty look, the racial, the elf factor, the factor that they have some of the most popular classes minus warrior, and the pretty look.