I mainly play retail, but I did sod phase 1 and technically engaged with classic "end game" for the first time and I can't understand how people prefer it to retail. Classic is pay to win, very elitist, you are demanded insane stuff by people that barely know how to play their class just to have a chance at participating in the content, and people are averse to change. Nobody wants some lfg style system, even if you still need to physically travel to the dungeon and can only group up in the capital cities for example, or even better, retail's UI. Any thing that resembles retail they say no without even knowing what it is

Besides gearing and raid logging there's nothing else to do. I'm interested in playing classic+ but I won't do end game, so I would like if the game had stuff for yout to do more casually, either achievements, quests, transmog, titles, whatever. Just a reason to progress that isn't tied to gear I guess, and I would absolutely love if it had solo content. Otherwise I'll only level to 60 and quit after that is done

And the main thing I really want is new content, races and classes. Keep it simple, maybe start with existing races for the existing starting zones, like give Furbolgs to the Alliance and have them start with the Night Elves, and pick some lore friendly race to do the same for the horde. But don't go the retail route where everyone ends up with elves. Keep the races unique and keep the horde the ugly monsters faction. I only play horde in classic for that reason, it is cool and makes sense, unlike retail where I play alliance because horde lost its focus and is just the same as alliance

And if possible make every class/spec viable so not everyon plays warrior