The Very Best Stuff -

    Wings of Honneamise
    Macross Plus
    Neon Genesis Evangelion ( a 23 episode tv series)
    My Neighbor Totoro ( a film by Miyazaki )
    Kiki's Delivery Service ( another Miyazaki )
    Grave of the Fireflies
    Princess Mononoke ( Miyazaki again, to be released theatrically soon)

The next level down -

    Tenchi Muyo OVA series ( and almost nothing else bearing the name )
    Video Girl Ai ( a long-time convention fave, now coming to the States )
    Gundam 0080: War in the Pocket OVA series
    Gundam 0083: Stardust Memories OVA series
    Battle Angel ( based on an excellent comic series )

The other stuff, (Ranma 1/2, Dragonball Z, Bubblegum Crisis, etc...)
has it's fanatical adherents, but it is a much more acquired taste.

Then there is the crap to be avoided at all costs -
    The Humanoid
    Project A-ko
    Crystal Triangle
    Towards the Terra
    Planet Busters
    Twilight of the Cockroaches
    ( thankfully, all this stuff is old, and may not be on the shelves
    of your favourite rental place)