The Hakbal EDH precon introduced some pretty powerful ones, like Ripples of Potential and Wave Goodbye, but there are also counter aplifiers like Hardened Scales you should consider
Choose a Background is a very specific version of the partner ability, which can allow a player to have more than one commander
Any deck that cares about self-mill will have plenty of options for getting cards into the graveyard, with Sultai-based dredge decks able to capitalize most readily
Sunstreak Phoenix You might want to avoid Sunstreak Phoenix if youre someone who doesnt care for the duty of tracking day and night in person
Too expensive for an aggro deck
A Narset, Enlightened Master player needs their combat phase, God-Eternal Kefnet and Meloku, the Clouded Mirror players need their draw step, and Edric, Spymaster of Trest players could change depending on their situation