Hmmm, I agree that Avatar: the Last Airbender, while not technically anime, may be a good choice. It seems a little childish sometimes (it is a Nickelodeon show after all) it does have an awesome story line. There's always good old Naruto, and Shippuuden after that, though it is definitely a commitment! D.Gray-man and Soul Eater were also suggestions I would second, I'd also say Baccano & Darker than Black, just because they're awesome. G Gundam is mecha right? There's always Eureka 7 *shrug*