Who plays with which heroes in the Inferno faction?

you can actually take Grol, and the Logistics skill will help you clear the map faster

No, Logistics won't help you clear the map faster; it just adds action points, which is practically useless without a strong starting army. For example, Grol is faster at the start.

I think that Grol is best used on large maps, as the teleport allows you to easily capture the mines you need at the beginning of the game.

Teleport isn't a cure-all either; you can defeat various golems without it, and it's useless against Druids and Mages. I thought about upgrading his Keen Mind skill so he would move before the dogs, teleporting them in, and they would finish the job, but often the dogs still move before Grol. His strength lies on tactical maps where you can outrun the enemy and capture their Castle guarded by a level 1 hero, easily defeating his army in the Castle and buying out those the player didn't have time to buy. As a result, the opponent is left without half of his army without engaging in the main battle, which may not even happen because they often surrender after that. So, Grol (like any logistics hero) is quite dangerous, but at the start, he's just as weak as any other demon, except for Deleb.
In the late game, he's a decent hero, but only with the right build; just being a meat shield won't make a difference. Marbas is an extremely unreliable hero; he's often completely useless. And no matter what anyone says, Deleb is good in the late game; the main thing is to get Defense so the demons can tank, and of course, good Dark Magic. With these builds, time works in the Machine's favor. In one battle, for example, a volley from a Ballista killed 18 Champions, while 66 Nightmares only dealt 6 damage each. And if you block the archers with summon spam and prevent them from killing the Ballista, the opponent will have problems.