I think my favorite is Sigma because his shield, absorption, and stun are all helpful in keeping himself from taking damage so I can focus on healing the rest of the team, and they can also be used to help us secure kills like placing his shield in front of supports to cut off heals, blocking a Widowmaker, using his stun to negate ults, etc. Plus I like that Sigma players usually seem keen to slowly but steadily push forward and stay with the group rather than run ahead out of range chasing kills.
Least favorite would probably be Doomfist. A good Doom is awesome and self reliant but I still find them often off by themselves, out of range of heals, while the enemy team is attacking the dps and supports and my attention is split so I usually ignore Doom and assume he’ll come back for heals but if he dies or we die it doesn’t much matter.
Least favourite: Doomfist. Good dooms are one thing, but too many just feed their brains out and do so well away from any chance to get into LOS. I want to help you, but it’s nearly impossible to set the conditions for that.
Ball players seem much more frequently to have that awareness to return for a couple of seconds for some healing. I mean, a good ball should rely on health packs first, but if you do take the time to return (and they do) I will happily heal you.
Most favourite: none specifically. Brawl tanks are fun to run with and I especially like to empower my Rein to win the mirror duel, poke tanks let you do other things more frequently and dive tanks make you feel good about jumping with them in terms of teamwork and it’s a lot of fun.
Just, no Doomfist, m’kay?