TF AD <3
I don't like to play with casters/ap champs, yet I played ap TF few times and I still find more valuable to deal 2k dmg in 2 sec with autoattack than to deal it with my skills and won't be able to cast them for those X seconds, which in team fights may be critical factor.
Also, as a dps TF you're not that much kill/assist dependet, you can just farm your way to full build only on minons, which cannot be done with AP champ ( yea yea, I know that Three Cards do shitloads of dmg and destroy whole waves of minons in instant BUT in late, when you're well feeded ).
Example of stats as a AD TF
10/3/3
12/6/11
AP TF
3/3/13
7/9/11 ( ._. )
and so on