Interesting points. I guess I liked and disliked all three for various reasons

…
The 2e racial restrictions were just dumb, IMHO. Also the fact that multiclassing was a non-human (maybe even inhuman

?) thing but dual classing was a human-only thing. Just plain weird.
As far as the XP getting split equally between two classes in 2e, I thought it was kind of nice actually. Doing evenly split builds in 3.5e was usually pretty weak, especially if mixing different types of classes, e.g., martial + arcane. You kind of needed Prestige Classes to pull it off.
2e was weird for having different XP thresholds for each classes, but when MC was involved it was actually kind of nice. Your Fighter/Mage would drift a bit with the Fighter pulling ahead, so you got your level ups at different times, rather than all at once.
I also agree with you that 3e favored classes were a headache and didn’t really provide much benefit. Kind of like a watered down version of 2e’s restrictions.
I think 3.5e was probably my favorite overall, because BAB, saves and skills progressed on a per-class basis on each level, and that felt pretty good. The 1st level-is-destiny approach of 5e is a bit less interesting IMHO.
As far as origins or level 0 was concerned, I think 2e races + kits were the ultimate in terms of fluff and flavor, while 3.5e was ok but not exceptional (it was just races, no kits nor origins, at least nothing significant), and 5e, ugh… I’m not a fan of the backgrounds + origins. I think it’s a good idea in theory but the background choices from the PHB and 2024 splatbooks are just so uninteresting. Makes me feel like my character is an electrician in the Sims or something. Takes a lot to bring these characters out of the gutter and into some kind of heroic story. Basically, it would have been better if the backgrounds were fully custom and the example ones they gave were optional rules. Technically it’s totally fine to run it this way, but it’s not presented as such and the digital toolings don’t necessarily support custom backgrounds very well, so it’s all meh in the end. Oh well, too bad.
What irks me about 5e is having feats and ASIs tied to class levels rather than character levels… I also find the spellcasting slot pooling slightly weird, but not in a way that it feels completely broken, just kind of odd. The slot rounding mechanics make no sense. But it’s a mild issue.
I also find that subclasses are too restrictive compared to 3.5e’s full classes and prestige classes… but again, not the end of the world.
Lots of things are simpler in 5e and it can be fun in and of itself to learn a new system, regardless of how good or bad it actually is… so we’re having plenty of fun with 2024 regardless of all the above complainery