Code Geass - I've watched/read and browsed around a shitload of Animes/Mangas don't think any of them can compare to Code Geass's storyline - This is a must watch imo.
Full Metal Alchemist Brotherhood - Epic fighting scenes, none of that fight; then stop mid way and talk; then fight again crap. Epic Story line, epic characters.
Sword Art Online - It's new, it's flashy, and it's a unique concept.
One Piece - Can't forget you, this'll take some dedication and patience to watch, as it doesn't really heat up until Crocodile, and then you have to wait quite a while for CP9, once you hit CP9/Enies Lobby stuff gets rolling. I tried watching the anime a few times, it didn't work. So I suggest the manga, which really took me in like straight away. Then after you're hooked you can watch the Anime.