I like team games. I like the split of responsibilities, the progress through all the tech stages, and adapting towards what my team needs.
I find teams of 4-5 players ideal for this. With more players than that, my impact on the game becomes so tiny that the game result might as well be random. Any less, and it tends to lead to every player having to do everything (large mental drain -> not something I enjoy as relaxation after work), and games being more prone towards mostly t1 stage.
So it's just a personal preference toward 4-5 player teams. 2v2 is too much like 1v1 for me. And I don't enjoy 1v1.