Mike's so high up on this list because he fills a role that white has been needing for a while now: good, unconditional creature reanimation, and this ability alone makes him an incredibly powerful Selesnya (green and white) Commander
Add to that the ability to put a counter on something, and this card just feels like it will do a ton of work
But please note that the one leader that doesn't include Red, (Atraxa) is the most played of them all
This deck is remarkable powerful with powerful draw effects, removal, counter effects, and much more
It also plays nicely with cards from Modern Horizons 3 that trigger when counters are placed on them like Evolution Witness and Fetid Gargantua
Golgari Grave Troll is a great way to mill cards in Dredge decks, enabling the decks primary strategy