Naruto Shippuuden
This is the first anime that comes to mind mainly because I am still in the process of watching it, and have been watching it since it first came out. I have seen both the Japanese and English version, and like both equally. I get really irritated when I hear people condemn English dubbed versions of animes to hell because they like the original Japanese version better. Sure in most cases it's true, especially for animes where the main characters will have distinct voices like high pitched and whatnot. But there are several animes which I prefer the English, such as "Fruits Basket" and "Inuyasha." And it's so much easier just to watch the anime without having to read anything every scene. On the other hand one anime English dub that made me cringe was "Outlaw Star." Regardless, I like to keep an open mind.
For "Naruto Shippuuden," I watch the Japanese version because it's much farther ahead! The story line is great as well as the action scenes and strategy elements. At the end of every episode it is always a cliff hanger and I die to the see the next. The writers also kept it realistic and deaths happen throughout the series to who you wouldn't expect. And to who you will miss. Characters develop nicely (one of my favorite elements) and you easily find yourself routing for certain characters throughout the story. I am currently at episode 143, which is the last one to be released so far. The few episodes leading up to it is MIND BLOWING. I cannot stress it enough. There is a certain element throughout both the "Naruto" and "Naruto Shippuuden" that turns upside down and you are left dazed and confused. I hope I'm coming across all right because I'm trying to write this in a way without giving anything away.
All I can say is, if you like adventure/action, drama and comedy, you will love this series. Of course, I definitely recommend watching the pre-series "Naruto," which leads up to "Naruto Shippuuden."