I've been in just about every online community there is since the original bulletin board days. I also do primarily PUG content in this game, and I can say with a fair degree of certainty that for me at least this is one of the best overall communities I've seen in a long time.
Every community out there has it's bad apples, that's just people in general. But here that's seemed like the exception, not the rule. My interactions in ffxiv have been almost 100% positive. My first week playing the game someone gave me a free mount. We talked for a bit and they seemed like a genuinely nice person. You might say "that's just one person and most people aren't like that" and I would have been inclined to agree with that if most of my interactions with people hadn't been pretty much the same. Just normal people being decent to each other and having a good time. The general sense of mirth and whimsy is really strong around here and it has been a serious breath of fresh air.
Like I alluded to earlier, even the PUG content has been more relaxing than others I've played. In dungeons or even raids, everyone always seems to be having a good time and wanting to help others learn, etc. People almost always greet each other at the beginning, with usually having some commentary along the way. When someone messes up or doesn't do well, people don't start raging at them calling them a terrible person with various epithets, etc. Quite the opposite.
Even the little things like Leap of Faith at the Golden Saucer with people cheering others on at the finish line with dances and glow sticks. It really has been a good time for me.
If all you see is negativity wherever you go, you'll be naturally drawn to it and you won't find anything else. This is coming from someone who was an extremely angry person for more than half his life. I get it, I've been there.