I'll select an anime that I watched before the last 5 years. When I first saw Serial Experiments Lain on Anime Unleashed (Tech TV) back in 2003 it blew my mind. Despite growing-up on Toonami, Lain and the other shows on Anime Unleashed were my introduction seinen anime pre-Adult Swim and this show's mind-screw concepts and prophetic warnings about social media before social media had been invented still leave me amazed.