I’m sticking with Mojave on my 15” MBP Mid-2015 mainly because it works and still has iTunes and Dashboard. I mean I rarely use Dashboard but there’s a certain nostalgia when I accidentally hit F4. Ha! The only 32-bit games I would miss are Doom 3 (have it for PC and PlayStation), Shadow Warrior Classic (also have it for PC), and this Gunship III - USS Constellation carrier-based game from the App Store (my father served on the USS Constellation so somewhat sentimental about the game).
Other than that, nothing really keeping me from Catalina or Big Sur, except that I’m not a fan of the Big Sur interface updates and everything works for now on Mojave.
I have the Henge Docks horizontal mechanic dock which has been great (but not compatible with newer MacBooks) and I like having MagSafe, ports, and no TouchBar so will try to live with my current MacBook for as long as it will do what I need. I’m not a developer or gamer and find that 2.8Ghz 16GB 1TB M370X+2GB is more than enough for me for now.