Naruto mostly, but I also watch ,or have watched: Bleach, Inuyasha, One Piece, Rurouni Kenshin, Pokemon, Death Note, Ranma 1/2, and many others that I'm to lazy to list.
I've watched loads of anime, past and present. This to the point, I never stop watching them. Though, at the moment, I've been re-watching APH and SZS constantly -- my favorites.
Axis Powers Hetalia
Kuroshitsuji
Sayonara Zetsubou Sensei
Junjou Romantica
Ikoku Irokoi Romantan
Okane Ga Nai
Maiden Rose
Katekyo Hitman Reborn!
Higurashi no Naku Koro ni
Ouran High School Host Club
Paradise Kiss
Death Note
Hellsing
That's all I could list from the top of head, but that's not all.
I'll include manga in my list to keep track. And they're my favorites, not just the ones I've seen. The abbreviated forms are in brackets.
• Neon Genesis Evangelion [NGE]
• The Melancholy of Haruhi Suzumiya [TMOHS]
• Lovely Complex [LC]
• Claymore [CM] - manga
• Gintama
• Monster
• Angel Sanctuary [AS] - manga
• Detective Conan [DC]
• Eyeshield 21 [ES21]
• Vampire Knight [VK] - manga + anime
There's probably a bunch more that I've forgotten. AS and CM are two of my favorite mangas. I have an intense dislike for most of the "popular" series for no apparent reason.