My favorite is always subject to change, but at the moment it's Sword Art Online.
It's a very amazing anime about a boy named Kirito, who is trapped in a virtual reality MMO called Sword Art Online with ten thousand other people. They have to fight their way through one hundred floors of the floating castle Aincrad in order to set themselves free. And the story doesn't even end there. It's a wonderful story filled with action and romance. It's my most highly recommended anime title.
You can watch a trailer of it here:
It's always changing, but currently, it's Trigun. Just a plethora of plot twists, a soul clenching story that will keep you at the edge of your seat. However, the first 3 episodes make the anime look terrible, LOOK BEYOND THOSE EPISODES! It gets better.
Mine is probably either Dragon Ball (Z), YuYu Hakusho, or Inuyasha. They were the very first anime series that I ever saw, before even Pokemon (I was like 3 or 4 when I saw them). I have very lenient parents.
Detective Conan. Its definitely not the best anime as the filler is just on a ridiculous scale, but the plot is good enough to keep me engaged.The anime will show about 5 to 8 episodes dealing with the plot. Then we'll get 8 to 15 episodes of meh filler. Then 4 to 8 really good episodes that don't necessarily have to deal with the plot, but are still really good. Then 5 more episodes of filler. Then 5 more good episodes. Then five more filler. Then we've finally made it to the plot again. Rinse and repeat. The problem with this anime is that it needs to end, but nobody wants it to. The creators can just keep finding details to add and it'll make perfect sense. They only address the plot every 25 episodes, so the story is literally moving at a crawl. It's at over 650 episodes now with over 10 movies and its nowhere near the end. You'd think we fans would stop watching it, but the episodes that involve plot are so good, you can't help but keep returning. Basically it has meh filler. Great episodes involving main characters. And on the edge of your seat, oh em goddness you're so glad you didn't stop watching this anime, plot episodes.
After Detective Conan its Hunter X Hunter and then Yu Yu Hakusho.
Amazing, suspenseful story.
Believable and beloved characters. Even if you hate a character, their personality is usually fleshed out enough so that you hate them with a fiery passion.
The art is beautiful, and the action frequent and intense.