Lost is the big show for me these days. It's ending next year with the sixth and final season, and whilst I'm going to miss it, I'll be glad it's going to end on a high.
Other shows I watch are Fringe and Lie to Me, both of which have their second seasons starting in the autumn. They are more standalone than Lost in their episode structure. Lie to Me is a real treat when Tim Roth rips apart some criminal to shreds, haha.