Tldr: As a fellow CLT area resident I think it'd be silly to go with something other than AA. I can't think of any compelling reason otherwise.

The Big 3 domestic airlines are all about the same for overall experience, IMO. For some years now I think DL has a slightly higher percentage of one-time operations compared to AA and UA, but I would have zero desire to add a connection in to basically every flight I'm taking. No way would I give up all the non-stop service; even if a flight gets a little delayed you know you're gonna get where you're going and not have to worry about missing a connection.

Moving on to status and upgrades...

Status: Segments no longer matter, nor miles flown. LP's / status are purely a function of money spent. Huge multiplier on money spent on AA airfare, but you can accrue it through CC spend as well.

Upgrades: I've been Platinum for a few years, and cleared PPro this year. I'd say I've had a reasonably good success rate on upgrades, honestly. But it is very much a function of where you're flying and when. Some routes or times of day there's ample availability and you clear well in advance. Other times you get to the gate and see that there's a list of 20+ people vying for the one last first class seat on a 319 😂