Every F2P game I came across to and played for a long period of time either turned into a cash cow/Pay-to-win, completely shut down or deserted with spider webs.
Digimon Masters Online was fun as hell, as long you got enough money to burn on it and the money needed for it to make it enjoyable and doable (in my own experience) required a monthly fee of cash shop items, Evo aura, experience boosts and stuff like that.
Rusty Hearts was a game with a lot of potential, it had a cash shop but wasn't really needed if you knew what you were doing and ended up being deserted, but had a lot of imbalances and such as well.
Tales Runner was probably (in my opinion) the most enjoyable F2P game I ever came across to, and you know what fate fun games awaits you - a complete shut down.
I only play League of Legends from time to time, other than that i've completely discarded the F2P community as a whole.