My own blog! Why? Because it would be better if I start building from scratch and learn from there. If you give a random untrained blogger any popular blog, he will just drive it down!
Of course I love all of my blogs and love having them, but when you ask this question it's pretty much equivalent to "What business would you choose if you could have any one" since the popular blogs are just that..businesses. So in that case, I'll take the NY Times Blog(s) , Huffingtom Post, Politico, C|Net, and Gizmodo. May as well shoot big
Actually the question is pretty interesting. I already have my own blogs, but I would love to own Smashing Magazine