The Modern Horizons 3 set is chock full of powerful Magic: The Gathering creatures for Commander, other Eternal formats, and Modern. These are the three commanders I'm most looking forward to building around.
Epic Commander game using Modern Horizons 3 decks
In a Green and Blue (GU) Ramp build, Nadu, Winged Wisdom is the bird for me. The Legendary places an untapped land onto the battlefield or places a permanent in hand whenever a creature you control is attacked with a spell. This ability can activate up to twice per turn, per creature. This means that each creature that is attacked gets to activate Nadu, Winged Wisdom's ability twice per turn.
I think the possibilities for Nadu, Winged Wisdom are endless. Green and Blue are MTG colors with a lot of bounce and protection spells, all of which trigger the Bird Wizard ability. You can add Equipment like Lightning Greaves to your build for additional triggers and mana dorks like Delighted Hafling to reach Nadu. You can even play new MH3 cards like Flare of Cultivation, sacrificing the Hafling, to reach even more lands.
Landfall cards will flourish under the leadership of Nadu, Winged Wisdom. Beanstalk Giant is a must-have, along with Ashaya, Soul of the Wild and maybe Cultivator Colossus at the top.