Combat would be my favorite for sure. I love multi-crew, combat focused gameplay the best. Working as a team to utilize a monster of a ship to its fullest potential in combat.
I also like flying smaller ships in combat, but will admit I'm probably not to good at it unless it's PVE. FPS is also something I'm interested in, but don't have any experience in.
Exploration is an interesting idea too, but I'll wait to see what ideas are actually implemented in the verse before I start diving to deep into that.