I like 5v5 more. As a tank I have more control and don't have to rely on another tank to pick a correct character or be useful in general. The latest patch fixed most issues with a tank and you don't explode when you blink. Sure counterwatch is still issue, but this same issue existed in OW1. Queue times reduced by 60% is a huge change and I rather spend my time in game than waiting in lobby.
I am interested to see what experiments they are going to try. Based on their wording they might try some kind of mix of a role lock/open queue and that could be interesting. I miss playing Pharah and changing to Winston after enemy picked 3 hit scans. I really hope they don't waste too much time trying to make 6v6 work. I like that games have less people in game since that gives you more agency and have less people to focus on.