Chrono Trigger and Earthbound being too rich for my blood, and having already picked up Mario World, ALTTP Zelda, Super Metroid, and Uniracers, what games would do you think I should try to collect? Anything still "playable" meaning still holds up as fun these days?

Tetris Attack is one of my favorites. Also, Secret of Mana, maybe?

super mario kart and NBA jam are still out in my collection constantly.

Super Mario Kart and Final Fantasy III. Possibly Secret of Mana but I've never actually played that.

All 3 Donkey Kong Country games.

Maximum Carnage is neat because it has a red cartridge. Mighty Morphin Power Rangers was a cool brawler so that is probably still fun today. Other then that I remember loving Scooby-Doo Mystery as a child but that probably doesn't hold up.

FFII, III, and MQ. Terranigma.

Home Alone. For the top of the stack. Possibly in a gold case, with platinum/diamond trim.

Yoshi's Island

Super Metroid

Killer Instinct

Mortal Kombat 2

Tales of the mystical ninja

Ninja Warriors

Ninja Gaiden Trilogy

Maximum Carnage

Serparation Anxiety

King of Dragons

Final Fight Series

Samurai Showdown Series

King Of Fighters

Secret of Mana is an absolute must. The original three Mega Man X games are also very good, better than anything post-MMX4, easily. Yoshi's Island, still one of my favorite Mario games of all time. The Donkey Kong Country games are good fun, as well, especially the first two. Harvest Moon is a personal favorite, but it's not necessarily something with universal appeal, admittedly. I'd recommend both Final Fantasies and Super Mario RPG, but if Chrono Trigger and Earthbound are too much for you, then I can't see you getting much play out of them. F-Zero and Mario Kart are both solid, even if at this point I wouldn't consider either of them the best their franchises have to offer. Aside from those and the ones you mentioned, I can't really think of anything else off the top of my head. I know I played a lot more growing up, but fuck if my memory wants to work right now.