There are a bunch of them.. all the animes I watched as a little kid in the 90's and of course Rurouni Kenshin which I watched recently. And there are some specific moments that always me feel a but emotional just by thinking of those moments.
In Sailor Moon it is the moment when Usagi and Mamoru reveal their secret identities to each other the first time. Kagome kissing Inuyasha in the second movie. Jingorou falling off the ship in Basilisk, I almost cried when that happened(!). Ashitaka and San giving the Forest Spirit it's head back in Mononoke Hime. Kenshin leaving for Kyoto in Rurouni Kenshin.
Actually, I believe I would keep some titles in my heart, but many for their own reasons:
Peacemaker Kurogane - it's just fun, lovely animation, great historical adequacy and it's incorporated in a good fictional story. Lovely adaptation of real people into great characters.
Naruto/One Piece - just the best shounen anime ever.
Bleach - for it's the anime that really hooked me (I have a really nice story of how i watched an AMV, linked in a work-related forum member's signature) to anime and manga... and then feeeeeeeeeeeeeeeeel so hard, fast and steepy that I don't even want to watch the last 3 episodes - it's such a disappointment.
Memorable, when it comes to no emotional reference, I would name:
Ghost in the Shell (the original)
Laputa: Castle in the Sky
How's Moving Caste
Sengoku Basara - so much damn good fun!
I don't care what others will say. I have my own idea f memorable.
Gosick and Death Note are the most memorables for me
However there are some memorable ones like Steins;Gate, both of Code Geass (specially R2) and Durarara!! XD
I haven't finished Hyouka yet but I think it could be one of the most memorables ^_^