Well thank you this thread. I thought I would just take a look at your list and see where I compare to you. For reference I stared playing in 1e/ BECMI in the 80's. I've played 1e, 4e, & 5e. I took a substantial break from RPGs between 1e and 4e (the game that brought me back to D&D).
1. I almost always aim for campaigns that last several years.
Me to. My current campaign has last since the beginning of 5e.
2. I never run any adventure as written and tweak everything.
Me to, with a caveat. I don't really run published adventures. I may borrow a bit from a published adventure, but everything is in our homebrew world.
3. The majority of what I run for 5E is stuff I have converted from 1E or 2E or that someone else has.
Not me, see my response to #1.
4. I have a list of available PC races that is more restrictive than the 5E PHB (but sometimes unlock other possibilities through the course of the game based on in-game events).
Not me. I had giants, minotaur's, and unicorn PCs back in the 80s and I still allow any intelligent creature as a PC option.
5. I have a hard time imagining D&D without multiclassing (except for BECMI, which had the original version of what I'd called prestige classes for switching things up as you advanced).
Not me. I could easily play the game without it. My current group doesn't have any MC characters.
6. While I love the stories that emerge from D&D sessions, I do not try to make the game fit "story beats" or narrative conceits - I play to see what happens - even if "what happens" is a TPK on a random encounter.
Me too. Nothing to add here.
7. I eschew most cinematic comparisons and don't think of D&D as an "action movie." While there are certain scenes and events that might fit in an action movie, that is not the aim. I describe everything from the POV of the PCs (no cut scenes to what the villains are doing, for example).
Me too - generally. I do sometimes to travel cut scenes (or I have done them - not so much anymore).
8. I think of mechanical balance as a general neighborhood to aim for and not some kind of granular precision that can ever be achieved. Some restrictions or benefits (like slower speed or darkvision) are more about shifting the tactics between individuals and developing a group approach.
Me too. However, I go a bit further. I don't do class design, but I don't worry about balance at all when I do race design. I design them for how they make sense on our world, not game balance. Just not an issue with my players.
9. I don't think every encounter should be designed with the notion of allowing every PC to do their best thing (or even allowing any of them to do their best thing) and definitely not every round. (Basically, I design the encounters that make sense for the scenario and let the players figure out if they can use their best thing - that's their job, not mine).
Me too.
10. I still calculate XP. PCs have different amounts, but are in the same neighborhood.
Not me. I haven't used XP consistently since the mid 80s. I always give it a try with each edition, but quickly abandon it.
11. I am not a fan of VTTs and remote play (though I do the latter when necessary and use Owlbear Rodeo a little bit).
Me too. If I can't play in person with my friends, there is not really a point for me.
12. Nearly every magical item introduced in my games are designed by me, not from a book (or highly adapted/revised versions of what appears in a book). They are never for sale. They always have a history. There are rarely magical items that make common everyday tasks easier. Magic is magical and for heroic action.
Me too - with regard to how magic items are introduced. It wasn't until 4e that I started designing my own magic items and that has continued into 5e.
13. Travel, exploration, and resource management are a core part of the game.
Not me. This has become more of thing in 5e for me, but in 1e I didn't care about those things at all. The idea of including travel and exploration in our campaigns really started in 4e and picked up from there.
14. Players can contribute to "world-building" through their backstories (though one isn't necessary) but mostly through their inquiry during play.
Me too. Though I allow other forms of contribution too.
15. I play with alignment, finding it a useful shorthand for running NPCs and a guide to help players consider the consequences of their behavior. For example, this didn't happen, but when the party's neutral good bard was considering killing a defenseless captive because of the inconvenience of guarding her or bringing her with them, I was ready to ask for the player's character sheet, and cross out the "good" part of the alignment and hand it back with just "neutral." I never say "You can't do that because of your alignment.
Me too.
16. I like long combats and tactical play - cover, ranges, verticality, difficult terrain, and other obstacles and aims are often a part of combat.
Not really. Those things a fine, but I am more interested in group fun and my group is not really interested in those things.
17. D&D should be challenging.
For the players or the Characters? I agree it should be challenging for the Characters (difficult encounters or tasks, substantial risk of failure and/or character death, etc.), but not so much for the players. My guiding principal is to make it fun. When running the game as a DM I want to have fun, not challenges, and my players are generally the same. Things can be challenging, but that is not generally what I or my players find fun.