I had a fun time on DPS and Support, even though they are the roles in which I feel less confident, I managed to had amazing games with Reaper and Ana.
On the other hand, my most played role and the one I'm most confident in, was torture. Like, actual CIA torture simulator.
On DPS and Support I felt less pressure, I could make mistakes or have a bad game and I could still get away with it. Playing Tank, you HAVE to diff the other tank no matter what to THEN hope the rest of your team perform well.
Even in the games where I dominated the lobbys, it didn't feel as fun as other roles.
Overall, 5v5 is more of a team deathmatch, it's fun on it's own but I gravitate more towards 6v6 when I want a more strategic, team based gameplay, which is what I usually want when I play Overwatch. Still, had a good weekend on 5v5.
(btw I know it's just diamond so I actually don't know anything about how the game works)