Perez is one of the better Cabinet Secretaries in recent memory and I'd like to see him run for elected office in the future (personally, I think he's one of our best options in 2020), but he doesn't want to be Chair and isn't running out of his own free will; it seems like he was pretty much bullied into it by business interests terrified by Ellison, and it's clear that his campaign for Chair is little more than a proxy by the departing administration to maintain control of the party. Ellison, in addition to being a Massive FF in Congress, has a clear plan to reform the Democratic Party both ideologically and in it's core structure, and having a prominent Muslim political leader is more important than ever in the age of Trump. This really isn't a difficult choice, IMO.
Amazing point.