I haven't delved deep in fandoms of most games, but Final Fantasy XIV has a very nice community.

Linux?

I have at this point roughly 1.6k hours in a bunch of Monster Hunter games, though by and large the vast majority of them are in Generations and Generations Ultimate. I've never liked concerning myself with meta builds, certainly not in a cooperative PvE game that I regularly would play solo.

Now I'll preface this by saying I've made some lifelong friends in the community, one of which I traveled halfway across the US to visit a few years ago. I don't think the community is all bad, but I've found so many people who will do very little other than try to minmax DPS build via the current meta and shame others for not doing the same.

One not so bad instance I had was when I was trying to break into some higher tier armors. I was going into a fight that I figured would take a long time, knew was going to deal a decent bit of burst damage, could easily knock someone out after that burst was dealt, and most importantly had 3 people joining. Because of these factors, I went with a build where I would primarily support everyone else, then try to keep myself alive, then any time in between those priorities I would try to deal some damage. A large portion of my armor was kitted out to increase the effectiveness of my items, have them affect my teammates, make my items have chances to be reused, then I set up my inventory so I was carrying a lot of healing items and could craft more when necessary.

One of the players in that 4 man squad I remember specifically trying to shame me for bringing a lower damage weapon (chosen because it had more skill slots), having significantly lower armor rating than the others (because I only had mid game support armor, not late game), and for not dealing much damage (because I was trying to keep him and the others alive). I say this one wasn't too bad because I also remember specifically that others in that very party pointing out that although I may not have had much armor it didn't matter much since I didn't engage much and they had noticed how much I was keeping them alive which would have otherwise failed us all the mission.

The worse situation I remember was getting sent DMs about how my build was bad, I was using awful skills, I had one particular armor set that was "a trap for new players", and to "please just use [x] armor set". They didn't like I was using three skills each decided upon because they would fix reasons I kept getting combos interrupted then killed and told me none of them were necessary because "if you're in the right spots then you won't need any of those",aka "git gud". I could somewhat understand this mentality if we were in a PvP competitive setting, or if we were in a group together actively working to speedrun this monster, or if I had asked for feedback on my armor. This entire discussion came about because I was trying to share with the wider community: "hey I just found about this neat skill exclusive to this armor set!"

I don't know how it is these days but a cool Fandom used to be eve online. The game sucked. 99% of the time you didn't do anything. Literally. Like to gain isk(money) you could go mining, you would go to an asteroid, click it, activate mining laser, wait, transfer ore to a hauling ship, wait, repeat for several hours. Oh you want to attack someone? Go there, click on them, set ship to rotate, set ship to auto fire, wait to determine if you win or they do.

That said you spent hours in voice comms just hanging out with your group. Many people used the time to make art. There were some who made songs about the game. Many people made life long friends as they were just talking every night for a few hours. This also led to a lot of creative incidents, like the guy who created his own insurance company for in-game property.

There were some assholes. One notable one being the guy who damaged the literal physical obelisk the company made engraved with all the player names and showcased at their convention. He scraped and carved a person's name out who he was fighting with online. Didn't hear the end result but I know the company was looking into legal repurcussions.

Plus there the added fact that you can buy a month of game play with RL money or with in-game money and things which are destroyed are gone for ever. That means you can calculate a ratio between in-game and rl money and know how much money that ship you just blew up cost.

The cruelty squad fandom was insane with people dressing up in business suits for lets plays to get in that CEO mindset.

Also I find it amusing that most of the fear & hunger fandom is queer & horny.

Marvel Versus Capcom 2/3. In general the fighting game community is very strange already, you have your street fighter players, but then you also have your smash players, your guilty gear players, your tekken players, your mortal kombat players, it's quite a mix. Then there's the MvC2 fans, this group has been around the fighting game community for a long time and this game has really got to cult status because of some crazy fun mechanics it has, it's just very fun to play and crazy to watch competitively. Anyways, they are a wild group.

Somehow nicest and meanest simultaneously is Trails probably in my experience lol. Trails fans love Trails but also hate it and hate you for not liking the same games they do. I wish there was a good Trails community somewhere.

Halo fans. Some of them are either Neo-Nazis/n-word users or the equivalent of your average Star Wars nerd, no in between.

Coming from LoL/Dota2 to Heroes of the Storm was like going from ninth circle of inferno to like second or so. Mobas are still cancer imo, but transferring to a nicer community felt great.

Left 4 Dead 2 unfortunately has been consumed by what seems a community of Russians and Germans. Neither of them are nice to you regardless of what side you play on. They're good at game tho.

One of the greatest communities I've participated in was an almost dead game of Town of Salem. Due to how small community is, people are generally nice to each other and just want to have fun playing this game. This doesn't mean that there are no bad actors. In fact there are plenty since game is f2p. But they are usually quickly dealt with.

I played Undertale and was kind of underwhelmed. The fandom would have you thinking it was the greatest game ever made

The Batman Arkham series. The series ended a while ago and the subreddit "devolved" into a giant meme, but if anyone has a serious question about something in the game they get the most helpful answers all the time.

Barotrauma was the meanest. You ask one question and the author of a mod throws a fit.

Team Fortress 2 players are kind of the three at the same time ?

Silly and weird, fairly chill and nice overall. But the bot crisis showed an AWFUL side of this game too...

mmos were the only game specific crowds I specifically engaged with really. Mostly pretty nice. I mean mmo's are basically social games so presumably people want to be social.

Last time I played No Man's Sky players were pretty nice.

Project Moon has all 3

DOTA 2 players might be the meanest. The game includes a reminder at the beginning of the match just for regular players to be nice with new players. That tells you a lot about the community (and, of course, the reminder is mostly useless). The match-accepting button gives some information and tells you the way your allies and enemies (in a single grade) normally behave, and pretty often they are in a red color that says "disruptive". It's bad. Unhinged chat and sometimes voice chat.