So after he got a couple of nerfs, is it still worth it to Play AP Kog or is AD better now?
(I know they have different roles)

He;s good you just need rod of ages, tear of the goddess, and holy grail..

bamp

Is this a question about how is ap Kog in general or on TT? In general I say he is still viable after his nerfs you just need tear/chalice/catalyst combo to be able to spam your ult. On TT I found playing him bot was good and I could just walk up to mid and take a few pot shots at the enemy top which helped out my top.

I actually play him AD a lot more as his ult scales a bit higher with AD than AP and late game I end up using his other skills for utility.

the one thing i will say is ap kog is a god turtler

Lack of escape makes things problematic for him. You might have to run Flash+Ghost to be effective

R range... just go in mid and shoot it at top = win