Enhance is faster if you know how to play the spec, otherwise go Elemental.
ITT: Barely-veiled insults disguised as anecdotal evidence implying inferiority of anyone who plays a spec differing from one's own.
The correct answer is, of course, to play whichever you enjoy more, since you'll level much faster if you're having fun. No amount of silly "I HAZ TRIED BOTH AND THIS SPEC WAS CLEARLY TEH WINNAR" and various other anecdotal ploys will change that. They are both completely equal, and you should play what you plan to use as your max-level spec.
I went enhance as soon as I had gathered a set of gear from questing. Ele worked great until I was forced into heavy kiting or heavy healing. Kiting became annoying in some of the more densely populated areas and the healing oomed me. It wasn't terrible but enhance felt much better. Between healing storm/as/feral spirit I found it almost impossible to die while pulling 3-5 mobs. In the end both are ok. Enh just seemed to preform better.