I tried Vampire Diaries when it started (despite the fact that I hated the books - to be fair, the tv series is better than the books). I found it overly melodramatic. I like how Buffy uses humour. There's no humour in Vampire Diaries, it's all just "you lied to me!" and "how can I ever trust you!" etc etc Damon was kind of fun but those slutty bad boy characters always seem to get ruined once they fall in love and I could see that coming.
True Blood? I really enjoyed season one, but after season 2 it all got a bit too daft. So I gave that up too.
I've pushed my way through 5 seasons of Supernatural. I don't know why I never got hooked. I really love the funny episodes. I think it just takes itself a bit too seriously. That whole God vs The Devil bit wasn't really a hit with me either. Maybe it's because I'm an atheist, maybe it's because I just prefer Big Foot hunts, I just found the angels, demons and bible stories a total bore.
Walking Dead? LOVE IT! It's not about hot people giving each other sultry looks while agonising over trust issues and tossing in a whole lot of mindless shagging.
Walking Dead has great character development and is full of good dialogue, action, suspense & horror, relationships that happen naturally, not just for ratings - it rocks!