In no particular order (excluding Fallout 1, 2, PST) here are my favorite games I can still replay and enjoy to this day. I could go on to list influential/shit games of my youth like System Shock, Bioforge, 7th Guest, Worms, GTA Vice City, Legend of Zelda, Super Mario Bros, TMNT, Duke Nukem 3D, Blood, Bubsy, Gex, Populous, Theme Park, Sims, Quake, Dino Crisis, Wolfenstein 3D, and many others...but I won't.
Fallout New Vegas - The best of a bad situation made flesh so to speak. I have probably played this more than Fallout 2 mainly due to great mod potential. Plus after Fallout 3 the hardcore fans just needed a little break.
Shadowrun - the game that introduced me to dialog and problem solving/adventure game mechanics. The music still gets me going. The combat kinda sucks but it was unique.
Earthbound - The nostalgia carries this one I am sure. I love almost everything about it minus the part with Jeff and the ducks. That part drags ass a little.
Doom - Can you get better level design and gameplay in a FPS? I still play it a few times a week.
Warcraft 2 - It is a tossup between this Lords of the Realm 2, Lords of Magic, and Dark Reign, for playtime but Warcraft popped my cherry and the lore was great.
Resident Evil Remake - I am/was such a huge fanboy it is hard not to list the first two games along with this. THIS FUCKING GAME is still tense to this day. It was so fucking good it killed the Gamecube. Silent Hill 2 is a narrow second here.
Civilization 5 - It might not be as refined as 4 but it sure as fuck is fun to play. Mods help.
Metal Gear Solid - The gameplay is dated due to the controls, but I get a fucking hardon just playing the intro in my head right now. Oh God the urges...
Final Fantasy Tactics - Damn I need to restart my last playthrough of this which shows I still replay this. I still remember losing a game due to not using more than one save slot on the legendary one on one fight.
Vagrant Story - Underrated. Overlooked. Obscure. One of the best looking/sounding games on the PSX. FF12 brought it back into the limelight but I see no sequels and the world might be better for it. God knows they would fuck it up.
Super Castlevania 4 - The best playing non-Metroidvania game in the series.
I went light on RPG's due to where the thread was posted. I could throw in some Final Fantasy or Might and Magic, or Super Mario RPG of all things. Limiting myself to 10 in lists like this is futile. I still find myself wanting to namedrop Super Mario Kart or Wizards and Warriors (just did). I think when a game digs a hole into your nostalgia center of your brain it is hard to dislodge, but these are games I could still boot up and enjoy which is rare. It feels good when a game is just fun to play. After playing RPG's for so long sometimes reading pages of text fries your brain and you just want to jump and kill shit.