For me, it's either Kyle XY or Journeyman. Kyle XY was pretty entertaining, and by the time it had ended, I had been pretty much addicted for some bizarre reason, and that's why I was so pissed at the end of the series. If the show had continued, it would've been considered a cliff-hanger, but since it ended, it was just a push off a cliff onto rusty metal spikes made of Fuckyou. I didn't get to enjoy Journeyman that much, I think it was cancelled after a few episodes, but I thought the premise was intriguing enough to warrant my attention. Traveling through time, fixing stuff in the past, trying to hide it from the authorities, previously thought dead girlfriends, not necessarily exciting, but interesting and slightly captivating, so I was bummed when it unexpectedly ended, since it didn't have enough time to evolve into maybe something kickass. Of course, it could've been crap, but my point is that I didn't have a chance to find out. But that's just me.