TF2 mechanically and at it's core is a pretty great game. It does things that other shooters still can't compare and don't really have(that includes OW). Although the competitive style/format of TF2 is the only thing I can truly enjoy as there is far less chaos, randomness, and lag while it is also more organized, skill-rewarding, and fun.
It's also nice to stick around to see what's going on time to time and seeing what Valve does(whether it may never be enough or good enough). Sometimes there are interesting topics also and drama stuff(which I think tbh a lot of people have sticked around for forum-wise) to read.
And of course, the comp TF2 community that I grew up with years ago and known has always been an amazing one overall. The players, the contributors, the people who make things happen, and the many great moments we had was always an amazing part of it all. While there may always be some bad apples, there are always the good apples that make this game still fun to play. The community is more of a home compared to some other modern game communities, it's indeed a lot more special in a way.