I have 2 (personally biased because I’m part of both):

BMW E39: I’ve met some wonderful people through owning various E39's. There are very few egos in that community and everyone’s super down-to-earth. We don’t pretend to have the best cars ever, or the most reliable cars ever. We know our cars can be troublesome and sometimes costly to maintain, but we love them just the same. The E39 section of Bimmer Forums is still super active despite the newest E39's being 14 years old, and the oldest being 20 years old. Everyone’s so open to sharing their knowledge and figuring out how to do cool stuff with these cars, like custom supercharger builds or swapping M5 drivetrains into E39 wagons. I’ve met a ton of E39 forum people in real life and they’ve all been great. There’s something about this old 5 series that just brings people together.

Front engine 80's/90's Porsche (924, 928, 944, 968): Unlike the super-elitist air-cooled Porsche people, every front-engine Porsche person I’ve met has been super friendly and nice. They all love their cars despite them being a royal PITA to work on (have you tried changing the 944 clutch?). The other day I had a 30-minute conversation with a random guy in a Winco parking lot about his 928. They’re all super friendly at car shows too, whereas the air-cooled guys often act holier-than-thou (I’m generalizing a bit but this is based on my experience).

The common thing I’ve noticed in these two communities is a real sense of humbleness and camaraderie. Everyone helps each other out and nobody acts like their cars are the fastest cars ever (looking at you, turbo JDM guys). And very few people in these communities obsess over looks, preferring to go for clean OEM looks because we appreciate our cars for the way they are. No underglows, no flashy LEDs, just straight class.