I think the biggest issue a lot of these background commanders have is that, even when paired with a great background, simply execute strategies that already exist but in a worse fashion
BLADE OF SHARED SOULS This one made waves in 60-card Standard, which is a big ask of an equipment card if you think about it
Reckless Handing Reckless Handling mimics Gamble, but for a more narrow subset of cards
Most of the cards I see on her EDHREC page are +1/+1 counter support, big creatures, and cards that want to be in the graveyard
There are a number of goblin pirates, too, so its also a flavor win
Kozilek, Butcher of Truth Our only creature on today's countdown is this fun Eldrazi Titan that costs ten, has a nasty 12/12 body with annihilator four, and then when you cast it you draw four fat cards as a cast trigger so it cannot be stopped with traditional countermagic