Favorite Free RPG.
My absolute favorite free to play RPG is a MMORPG called Runes of Magic. What made it so much fun for me was the fact that as the player you could design your character around 2 classes instead of just one. Actual multi classing in an online game. With this there were certain abilities for each of your classes that you could only use when either of them were your primary class, but then there were abilities you could use even when your 2nd class was secondary. It made for some amazing combinations that could be very powerful.
As an example I played as a Priest for a long time but then Multi Classed into Mage where I could run around dealing lots of damage and protecting myself through my Priest abilities. It was tons of fun and made me a very scary Mage on the battlefield.