2010's going to be a great year for everything. Big Nintendo franchises (Metroid, Mario), big MS-exclusive franchises (Halo, Mass Effect), and big Sony games (Last Guardian, Heavy Rain). Then we're also getting great third party games like Bayonetta, and hopefully please god, Half-Life 2 Episode Three please please please.
2009 was good for the Wii though. If you're looking for reasons to own just one system, the Wii probably had the best, most varied lineup of exclusive titles all year. I think this has to do with the 360 having a slow software year (fighting and FPS genres excluded)- a lot of the big titles, multiplatform or otherwise were pushed back into 2010. The PS3 also had a good year and should finish similarly strong what with Trine and Ratchet & Clank still scheduled to hit.
It's been nice this whole year's been pretty slow across most systems. It's allowed me to catch up on my backlog and I haven't spent too much cash.