I'm liking hybrid, triforce+stacked rageblade gives you enough AP, insane attack speed and decent burst.
Plus his Q is just meant to work with these 2 items.
Also chalice + brutalizer are usually good starting items if you don't feel like rushing triforce.
And seriously, all these impossible 6 item super AP builds just don't happen unless you are smurfing or something.
You have to think what you will get next and balance your gear, a lot of times using an elixir is more productive than trying to save for another item.
Hell, even chalice first isn't always possible if you are facing ******ed cc and burst, making you rush mercs and abuse pots.
But my ideal build would be something like:
Boots, triforce, guinsoo, soul shroud, frozen heart, starks if none of other carries built it, and if not some pure damage item (black cleaver since you can stack the debuff pretty fast or some AP item like archangel's staff).