Final Fantasy 14 has really impressed me with how nice the community is. There are a few bad apples, but most people are totally chill, and bad behavior isn't taken lightly by the mods and devs. The community is remarkably good at self-policing, with other members reporting violations they see. Reports usually get a response within minutes or hours, rather than days or weeks.
New players are very welcomed, and aren't given a hard time for not immediately being experts at the game. Veteran players are usually happy to help explain things to new players, and many veteran players are marked as Mentors, meaning they're available for questions from inexperienced players. Simply stating "I'm new, first time!" when entering a dungeon with others usually gets met with welcomes and helpful advice.
Even PvP battles are fairly laid back, and players don't get all bent cos you're not as good as they are. Most players are just trying to have fun, and don't take it super seriously. You can admit you're a noob or a casual, and people won't bite your head off. There are hordes of players who only log in to play mini-games at the "casino", or craft and create clothes and fashion, or play music as a bard, or customize their private apartment, or whatever.
Free Companies (guilds, basically) are always recruiting, and tend to be pretty active. There are plenty that are geared towards new or casual players.
There's still the occasional weirdo or jerk, but they're few and far between, and usually pretty tame.