This may be a slight nod to cEDH on my part, but I also think that being a staple of the highest-powered Commander variant should count when evaluating a card
Few cards do precisely this while both delivering on the characters potential and telling a meaningful story
They wont gain or lose counters until you remove the card shutting off their abilities
All the way from Fifth Edition, it's Reef Pirates by Tom Wnerstrand
The amount of damage a Monstrous Rage can push through is pretty impressive as well, and I liked having access to those tools even if Id often sideboard it out
First up, there's Olivia, Opulent Outlaw, who makes treasure tokens when outlaws deal combat damage, and can turn that treasure into buffs for her whole gang of misfits