I kinda liked Gilgamesh.
He had the potential to have the kind of friendly rivalry with Thor that Thor has with Hercules.
Gilgamesh was a character that some interesting thing could have been done with. Way back when he confronted the Celestials and the Celestials sent him back to Earth wearing space armour of similar to what they wear with some unknown mission that he wouldn't talk about.
To me, this unrevealed mission is one of the most interesting dangling plot lines that Marvel has and I would have loved to have seen it tackled during his time as an Avenger.