[2019] "AP items are OP!" Items AP champions can build against AD ones: Zhonyas. Items AD champions can build against AP: Maw, Abyssal, Adaptive, Spirit Visage...

Locket, Mercurial Scimitar, Wit's End, Adaptive Helmet. And then to top it off, you can run Nullifying Orb in your runes and all HP items also hurt AP champions more than they hurt AD champions. Commencing Stopwatch is also the same deal in which it's for the most part better against AP champions than AD.

AP champions should have more items they can build to counter AD ones.

EDIT: People are saying it's unfair to use tank items in this comparison. You won't ever see an Orianna or Rumble buying tank items in high elo game. You will see Kayn and Camille and Gangplank and Renekton doing so.