I tend more toward American comics than Japanese comics but more Japanese animated series than American ones.
Since you're asking about the Japanese stuff, I still have a soft spot for the shounen heroes. Goku's undying (lol) dedication to training to protect his loved ones, etc. I definitely enjoy Dragon Ball (though Kai's the only series I've watched in full) and Naruto.
Love love love Trigun. (Does it show? >.>) The only Japanese comics I own are the Trigun trades localized by Dark Horse. I still need to buy into Maximum.
Other animated series I've enjoyed are... shoots... I can't even remember what all I've watched. Oh! Fullmetal Alchemist was/is a definite favorite. So good. So heartwrenching, too.
.hack//Sign is another definite favorite. I'm not sure why exactly, but I find the .hack universe very engrossing. I own some of the novels based on the series even.
Liked Hellsing a good bit. Surprisingly really liked what I've seen of Initial D (first two or three "Stages"). Liked what I've seen of Samurai Seven, Persona: Trinity Soul, Claymore, and Cowboy Bebop.
The latter I actually plan to watch in full with a friend sooner than later.
I'm sure there are other things I've watched/read that I'm forgetting (just remembered Death Note), but whatevz. This demonstrates my tendency toward mainstream series. Open to anything; I just end up tending to watch and enjoy those things.
Edit: Now following you on Twitter.
