Who's a good hero for Heronium?

I’ve been currently trying to get Maven to 10 stars but the process is painfully slow, so I was wondering if there are any Hero’s better than Maven for Heronium.

I would recommend Dog, Flatline , Drake , or even Richter .

Gauntlet: Dogface, good for all game modes too

Hard Mode: Nightingale is a must. The rest is up to you but farm as many heroes as possible

PvP Store: the only store which has no limits to farming gems. Imo, drake and mauler are the best, useful in PvP, also available in hard mode as you level up

If you are in a good alliance, maxing either Callidus or Galante allows you to get 15 heronium a day without really playing anything. Bounty events I can usually get around 60 frags for them plus we have multiple events where Alliance gems are rewards. Been the best source for me besides gauntlet.