There are a few sci-fi mmo's in development at the moment, Alizarin already mentioned Star Wars: The old republic, another which I've had my eye on for a while is called Earthrise, it's post apocalyptic rather than spaceships but I love all that myself! Signed up for beta a long time ago but won't be f2p. World of Darkness is also something different, that's currently in development, so for lovers of White Wolf and Vampire pnp RPG's it may well be pretty fantastic! It certainly looks like it will be. Anime lovers may find their thing in Shin Megami Tensei (Megaten for short), we're talking post apocalyptic Japan with demons here! It's based on a series of the same name. Megaten is f2p whereas World of Darkness won't be.
Fallen Earth is a subscription MMOFPS, I haven't tried this one myself as FPS + women rarely mix successfully! The Secret World may also be one to keep and eye on.
I know there are more, but these are the ones that come to mind as I type. As for me? I continue my long love affair with World of Warcraft.