Well, I don't watch Naruto too much either. I think it's very overestimated. About Avatar, yeah it's very nice. I've watched a few really worthy of watch animes. But it really depends on your likes. Hmm... For example, I'd recomend you to watch "Angel Beats", it's a very very nice and emotional serie. The only one that made me cry. (Lol really) Other really nice is "Fairy Tail". It's a very original one if you ask me. Hmm... other animes like "Full Metal Alchemist", "To Aru Majutsu No Index", "Hidan No Aria"... I'd also say "Zero No Tsukaima" but only the 3 first seaons 'coz they ruined it with this last one. Right now, can't think about too much names
Naruto before and now is like talking extensively and there's not much action. But that was just the first few episodes I've watched. I don't know about Naruto Shippuuden now. I'm surprised it got to 200 episodes and much more.
I have watched To Aru Majutsu no Index Seasons 1 and 3 and To Aru Kagaku no Railgun. Freakin' awesome. I have watched Zero no Tsukaima Seasons 1 - 4, High School DxD (Don't call me perverted, it's the action I want).
I am still watching Sket Dance and Haiyore! Nyaruko-san.
Hellsing ultimate ova's are great also like claymore , fullmetal alchemist: Brotherhood, soul eater...
As for longer ones they all have like something ruining them if you don't want to show commitment: Naruto = really really slow moving story Bleach = fillers , just those suckish fillers One piece = for a lot of people it's just to awkward Fairy tail is different , you should give that a try
Well, if you want some recommendations, here are anime that I've watched and liked:
The Melancholy of Haruhi Suzumiya Code Geass R1 and R2 Death Note Spice and Wolf The Daughter of Twenty Faces Ouran High School Host Club Soul Eater Hetalia: Axis Powers High School Of The Dead Kuro****suji/Black Butler Elfen Lied The World God Only Knows Yu-Gi-Oh + GX and 5Ds Dragonball + X and GT FullMetal Alchemist: Brotherhood Tengen Toppa Gurren Lagann Sayonara, Zetsubou-Sensei (and it's follow-up series' Pokemon Digimon (the Original and then most of the follow-ups and spin-offs) Bleach Kore wa Zombie desu ka? Durarara!! Ao no Exorcist To Aru Majutsu No Index To Aru Kagaku No Railgun Bakuman
Plus, in terms of anime movies I'd recommend: Spirited Away Howl's Moving Castle Most things by Studio Ghibli, really. Summer Wars
Also, just to correct something you said, Avatar isn't anime (at least not by the Western definition of anime).
It's just a cartoon. Y'see, by Western definitions, anime is a term that refers exclusively to animated series or films created in Japan. Other than that, there's no real difference, maybe a few stylistic or plot-element differences but nothing too divisive - I'm just being picky.
I will be picky with you. While anime and cartoon are just foreign words for the same thing, there are vast differences between the cultural aspects and the way a story is told in the Eastern and Western world. The reason that Avatar looks somewhat like anime, at least stylistically might be due to the last decade's progress in cutiefying everything to appeal to the costumers that have grown fond of the Eastern marked of shoujo and shounen material. The big eyes and big expressions are just that, but that doesn't make it anime, because it is made in a Western country. If it does, then you might as well make no distinction between them and just call it all cartoons. Which might be just as good, as long as you are consistent about it.
Also, what Avorne listed. I could probably list a bunch of others due to my years in that culture, but I would rather want to hear what you are looking for. Sounds like shounen/stuff for boys?
I hate displaying my more picky side otherwise I'd have probably said exactly what Cenere did.
Anyway, there are also others that I could list too, but I wasn't really sure what the OP was looking for so I just gave a mostly Shounen list with a bit of Shoujo stuff thrown in.