I'm not the type of guy who rewatch animes a lots. I need to forget enough of the anime to rewatch it, and need some nostalgia to do so.
But i've rewatched Card Captor Sakura and Serial Experiment Lain more than 4 times, and i will watch them again in the future. I've also re-watched Ergo Proxy, Lodoss 1st season and FMA 2003 exactly 3 times, same for the quasi-anime "les mystérieuses cités d'or", and will rewatch them again in the future. I have the DVD of all those series for a reason, after all... Can't say the same for Escaflowne, a good anime, but i'm not sure i i will rewatch it again, at least not in the next decade for sure. Thoses are my most rewatched, because I discovered them during my teenage years, chilhood for CCS, and therefore had enough time to rewatch them.
CCS is perfect when i'm in a bad mood and want to cheer up, BTW.
For the more recent stuff (less than 10 years), i didn't rewatched them a lots, because i don't have the nostlagia yet. But i'm sure i'll rewatch "Aquatope on white sand" a lots during my lifetime. Same for Ruri No Hoseki. And also the same for Noir and El Cajador de la Bruja, two old series i discovered a few years ago which mean i treat it the same as the recent stuff.