I do like Countdown, but Youthanasia is better I think! Much better! It's just heavier, more energetic, catchier, not as mechanical, etc.. to me. Dave Mustaine has said "If Youthanasia was released when Countdown was it would've been huge" or something. Last night I had a drunken argument with someone who was saying "Dave Mustaine's such a wanker, trust him to say that" but I'm inclined to agree with Dave I think!
I mean I think the first 6 Megadeth albums are all just absolutely awesome! Countdown is just my least liked out of those 6.