Top of my list would be TTGL... there wouldn't be an episode where nobody got punched, kicked, slapped, stabbed, whipped, shot or blown up.

As some have stated, much depends on taste. Over the years I've watched a ton of anime, all the way back to the original Astro Boy (am I showing my age?) when it was first aired back in the '60s, so if I tried to list everything it would turn into volumes. With that in mind, I'll stick to titles since 2000.

To start with, the three Key Studio releases (four if you count both versions of Kanon and Clannad: After Story): Air, Kanon, and Clannad. While all three were imaginary tales told a "slice of life" stories, neither of them were quick paced, but each episode was rick and full, and served to move the story along.

Next would be Kekkaishi. While it was an action tale, even when it would slow for back-story moments, it was always interesting and always left you feeling satisfied and wanting more. In fact, whenever I listen to "Take Over Destiny", "Training Days", or "Battle Ground" from the OST, from the moment I hear the smooth strings at the beginning, I'm tempted (and have succumb on more than a few occasions) to pull the series out and watch all fifty-two episodes.

Bamboo Blade is another... probably because it's just fun from beginning to end.

Time of Eve would have to be included. Between the beautiful art and the wonderful storytelling, it's an uplifting experience.

ef~a tale of memories remains one of my favorites and with the constant shifting between the stories of the two main characters, there's never enough time for an episode to become boring.

The same is true for H2O: Footprints in the Sand. When you open with one of the lead characters being beaten without mercy and end with her being hit by a train, it's hard to find anything boring in between.

Spice and Wolf (both seasons) is yet another. Every episode moves the story forward and lends itself to developing the characters. On top of that, the world they live in was rich and varied.

Then there's the list:

Glass Mask
Skip Beat
Mai Hime
Daphne in the Brilliant Blue
Witchblade
Gunslinger Girl
Guardian of the Sacred Spirit
To Aru Majutsu no Index (A Certain Magical Index)
A Certain Scientific Railgun (A Certain Scientific Railgun)
Nodame Cantabile
Saki
Shion no Ou (Shion's King)
Sola
Mission-E (I know... it was silly. But it was cute and so much fun)
Witch Hunter Robin
Shuffle
High School of the Dead (camp but well done for the genre)
12 Kingdoms
Parasite Dolls
Steel Angel Kurumi Zero
Tegami Bachi: Letter Bee
Asatte no Houkou
Yoku Wakaru Gendai Mahou ("the story of a girl who transforms all magic into pans"--delightful in ways I can't begin to explain)
Tokyo Magnitude 8.0, and
Blood+

There are more, but if I keep on I'll never finish this post.

sailor moon
death note
xxx holic
etc.2x

Gintama.

ouran high school host club and ultimately gintama

then theres hayate no gotoku :p

Code Geass
Ouran High School Host Club
Katekyo Hitman REBORN!
Kamichama Karin

Ouran High School Club

Eflen Lied
Naruto

And I cant think of anything else e.e

Dragonballz-Mostly because it was action after action it was kinda nonstop even the training was interesting and never had an episode that was boring
Sekirei-newer anime still has only 2 seasons out (about 27 epi) and about 4 seasons to go (about 48+ more episodes) but so far its been really fun and entertaining
Full Metal Alchemist-Oh wow this anime made you think and the action was very good gets confusing (alil) but deff not boring at all

To all the Naruto hating i believeing they are trying to say that even the filler have pretty decent action
Personally i cant put up with fillers i think they are the dumbest things but idk thats why in any occasion i much rather read the manga less or no fillers at all

Gintama
Katekyo Hitman Reborn!

Touch!
Cross Game
Bamboo Blade
Toaru Kagaku no Railgun
Great Teacher Onizuka

oh.. and the Kansen series!

Yu Yu Hakusho
Samurai Harem
Demon King Daimao
Black Lagoon

Ah! My Goddess Ovas.
Gurren Laggan.
My Dear Marie!

Ouran Host Club
Initial D
Lovely Complex
Natsume Juushinchou (and Zoku)
Durarara!
It is so hard for the long running anime not to have a few boring eps here and there. I see a lot of people picked Gintama, I been putting off watching it, but now I think I have to.

Code Geass, OHSHC, Gakuen Alice

Gintama
KHR
Ookami-San
Shinrei Tantei Yakumo
Shinryaku Ika-Musume