I like that they added this feature which shows your top three highest level heroes, but it does seem like it’s purely for show. 

My two best DPS heroes are Tracer and Sombra, and I have a lot of games where they both get banned. I’ll pick Tracer as my preferred hero, my teammates will ban Sombra, and then Tracer will get banned by the other team; if I pick Sombra as my preferred hero, the opposite happens. On Escort and Hybrid maps, I like to play Tracer on attack and Ashe on defense, but I can only pick one as my preferred hero, so the other does get banned by my team sometimes. 

I wish they would show the hero level cards before the hero ban and map voting phases. Also, they should show your top three heroes for the role you’re currently playing, not for all roles. That would certainly help with choosing more effective hero bans. 

If my tank chooses D.Va as their preferred hero, I’d naturally be inclined to ban Zarya. But if I see my tank is level 50 on D.Va and level 45 on Rein, then at least I know they can switch to Rein if the enemy tank does play Zarya. Or if I see that my tank is a Rein one-trick, then I’d know that voting for Gibraltar probably isn’t the best decision. 

TL;DR: I think it would be better if they showed the hero level cards prior to the hero bans and map voting. 

Why don’t they show these cards before/during the hero ban and map voting phases?