Short post, but my comment of the day is the realization that I'm reaching a point in my gaming life where it is actually more important to me that I am comfortable with (and by virtue of that, engaged with) the rules of a game system in a manner which I find comforting and consistent. This may be one of the reasons I have found myself only really looking forward to the D&D 3.5 game recently....it's a system that clearly was engrained --hell, burned-- into my brain over the course of about 14 years (especially if you include the Pathfinder 1E era). It helps, of course, that I was always in the camp of "people who played AD&D 1E/2E but who desperately wished it wasn't all such a mess" --for many, the arrival of D&D 3rd edition was the game we'd all hoped for, one which did D&D and fixed the edition issues before it.
Now, my love of 3rd edition today is tempered by a few key and extremely important details. As mentioned before one is that since it is no longer the end-all and be-all of the D&D world I have a lot more control of the content I wish to use for a given game. Second is that it's print cycle of life is essentially over; since I am not just going to Pathfinder 1E but in fact winding back the clock to D&D 3.5, it means that there is effectively almost no content out there for the game in current production I need to worry about (well, there are a few Raging Swan Press modules I'd like to retro-fit for D&D 3.5, unless RSP would be kind enough to upgrade them to Pathfinder 2E...)
So for me, having D&D 3.5 is a great mix: a complete work, a finished product, to which I can provide the level of DM control necessary to allot the right mix desired. It is also an edition of the game which rather ironically has more overall content and direction on how to add/use content in the game than any other current edition. This is a very round about way of saying that unlike in my Pathfinder 2E game where we essentially called the campaign at level 20, in D&D 3.5 we could keep going. Unlike in both D&D 5E and Pathfinder 2E, I don't need to wait for a new racial ancestry or template, because the game itself provides the foundational rules to make any species a character if desired.
3.5 has problems....key for me is you have to pay attention to sometimes annoying stacking rules, the grappling rules have never been intuitive or well explained, and the fact that monsters both can and must be leveled up like PCs means that there is always the temptation to turn NPC design into a time sink. But two decades of D20 derived systems have shed retroactive light on what is actually nice about some of these features, and also which ones don't really need as much attention or focus as you might imagine. If we muck up stacking on occasion it ruins nothing. Grappling rules can be quietly house-ruled to work more like Pathfinder 2E, or I just keep my old grappling index card handy for reference. Monsters being complex designs with class level options means I can spend as much time as I want messing with elaborate designs....as long as I feel like it. But the plethora of content both in print on the second hand market, in my library, and free online is insane; I am not wanting for readily available resources for this legacy game at all.
Ultimately, the best thing about 3.5 is the vast majority of my expectations in gaming which were forged in the 90's with AD&D 2E and solidified in the 00's with D&D 3 and 3.5 are well supported here....and that is why I realize that my enjoyment currently is based as much on the fact that I have accepted that I can have a comfort zone in an out-of-print old edition of a system as that I can at least relate to as any current edition system which may have stripped out just a bit too much for contemporary audiences. And the best thing of all is hey, I'm 50 now, I can enjoy what I want and not have to "keep up with the times" anymore if I really don't want to! I've got a medley of players I've been gaming with for 10-20 years or more, and we all have similar tastes. If they enjoy it, and see that it is where my level of enthusiasm lies, then more power to all of us.