I've been on a Cookie kick for quite a while now, so I'm really glad that he's been getting his own segments lately, like Crumby Pictures, and Smart Cookies, they've both been very enjoyable.
When I was little, Big Bird was my favorite, so it always feels like he was the first best friend I ever had. As a teen, I went through an Elmo phase: I enjoyed Elmo's World in the beginning, and Kevin just did a phenomenal job in bringing so much life to the character . . . but once the "Elmo takeover" starting setting in, the character lost a little of its appeal. Later in my teens, I went through a really big Grover phase, I nearly wore out my DVD of "A Celebration of Me, Grover," and I was stoked when he appeared on Jimmy Kimmel one night (and even got into a little tiff with Tim Daily).
I've also gone through brief little Snuffy and Count kicks in the past. But that's one of the things that's so great about SST, there's so many wonderful Muppet characters and they all serve their own little purposes and add something different to the show.