You can set TinyMCE as your default editor in 3.4.x but I am not yet sure about v3.5. That might give you a solution, but I suspect you will have to add the font in the settings of TinyMCE. Personally, I prefer TinyMCE, Atto is still too immature to be really useful. I have students with Irlam's Syndrome, and Atto just doesn't cut it for them. Don't get me wrong, there is potential for Atto, but just not as useful as it could be at this time.