IPS would always get my vote, I'm on my second IPS monitor and would never go back to TN. Currently have a Asus MG279Q, which I have had just over a year now and love it. I find it great for the games I play Battlefront 2, Vermintide and the IL-2 Sturmovik BOX flight sims.
When I was looking for a new monitor, the things I wanted it to have in order was. 1440p, 27", IPS, 144MHz, G-Sync/FreeSync. I didn't get the G-Sync version as I was not willing to pay over £100 for the option.