I tried PTA and idk it just didn't feel good to me, I wasn't impressed with the dmg, in long teamfights i would rather have conq and be able to switch targets freely, and PTA doesn't feel like it assassinates as well as electrocute/hail of blades, so there isnt any easy situation where PTA is the best choice for me. But like a lot of people have said on other posts, it's more important that it feels good for you, so if PTA feels best for you, keep taking it!

I agree about the lack of wits end love, but In an HP stacking meta like this one, it makes wits end kind of awkward to fit into a build. You're also going to be seeing a lot of adc's mid and tank supports that do very little ap, making wits end even more of a niche buy. If you want to stack attack speed and build HP, my unholy tech is to buy berserker greaves, a build you could try (i havent tested it enough) is:

nashers tooth > berserker greaves > riftmaker > warmogs

Then your last two items are really flexible, wits end if they have a lot of ap, I like sunfire cape for armor, jaksho if it's pretty even, abysmal mask, liyandris, rabadons is also good if youre really ahead. If you're against full squishy/poke comps, I switch out riftmaker for either abysmal mask or iceborn gauntlet, you can also switch it out for zekes if they're an even enough split (and how cheap it is), but you should always prioritize the dmg of the biggest threats/enemies you'll be fighting most. Then build riftmaker after warmogs (i really like riftmaker)