I'd love to see Black Panther, I think he's a really interesting character and he would be an awesome edition to the Avengers. If it was my line-up, I'd completely scrap War Machine and have the IP suit as just a robot for support, and then introduce BP, Ms Marvel and Dr Strange especially for phase 3, I can't see WM being very important - someone said it previously about him using just his mini-guns against the likes of Thanos, whereas Dr Strange providing magic alongside Scarlet Witch, and Black Panther for the added cool effect no matter what he does