I mean the later Delta zones are fairly random and its still a shit show. Which lines up with what researchers found when they've looked into it from time to time. Generally the window, middle, aisle boarding generally does the best outside a much more complicated "Steffen Method" or a "Slower first" method. For example:
https://arxiv.org/pdf/1108.5211v1
We tolerated Southwest's open seating and miracle flights (I took a Vegas to Florida flight once and Jesus himself must have been on that flight judging by all the people who could suddenly walk off the plane on their own) but I did like their orderly "Everyone gets a boarding number". Until they monetized the shit out of it so you had to add Early Bird to everything at purchase time to get a decent position. YMMV of course but we did a lot of Southwest flying via Companion Passes and basically gave up flying them. If you don't care where you sit then they're probably still fine but I've developed strong opinions about my seat choice so I'll stick with airlines that let you choose them.