Espgaluda - I'm currently taking a brave step into the world of bullet hell. Love this one. Street Fighter 3 Alpha - I got my son into Street Fighter and we enjoy learning new moves together. Amazing 2d artwork in these. Wipeout + Wip3out - Wipeout pushed the world of gaming into mainstream acceptance. Looks cool has great 90s club music and brilliant visual design. (I'm partial as I used to work with one of the designers) And of course it's got great gameplay. Sonic - Favorite game of my yuf. Golden Axe - Used to play this with my brother and we still do now and then.
(Also I'm playing through Super Metroid right now for the first time, I love the music and the different areas.)