Abathur is my highest sitting at something like 60 something
Dehaka follows at 50
Uther at 45
Chen and Jaina are neck and neck usually.
Dehaka though is probably my most recent main, alongside Uther. I play mostly QM.
Dehaka I feel is broken strong in most situations as it can be really hard to kill a Dehaka that doesn’t want to die. His usual role people expect him to fill is such a waste of his skills, like picking his minion essence talent at 4. Hero takedowns is by far the better option, even before it was buffed. He just has to be played incredibly aggressively and in your face. None of that Agi speed ambush crap. If he’s not balls deep in the enemy team, you might as well be playing someone else.
Uther on the other hand… Is broken in QM. Queue with a healer (so your team actually has one) and you can find your enemy with no tank while your team has one. He really isn’t a healer, not is he a full tank. He fills a middle role having spot heals for emergencies while being sustainable and able to land both finishing blows (holy shock) and solid CC.
I will add though, that I do not play one hero significantly more than the rest. I have something like 40 heroes above level 15 and many are high 20’s and low 30’s. I play a very large variety, preferring to avoid only the ranged assassin role except in a few select circumstances.
I mostly can play every hero in the game (lvl 5 at least everyone). In ranked I play mostly Johanna (maybe >70% games) but not in QM because she is not very fun. So u can consider her one of my mains