Okay, some solid ones and great ones, in no particular order...
Shadow of the NinjaShatterhandBatman: The Video GamePower Blade 1/2Batman: Return of the JokerMitsume Ga TooruMoon CrystalKirby's AdventureSMB 2/3 (the first is fine, but has never been my favorite)
Totally Rad (a little uneven, but I still like it)
Metal Storm (not my favorite, don't like the one-hit deaths, but cool mechanic)
Vice: Project Doom (very cool triple-genre game that apes
Ninja Gaiden)
Ninja Gaiden 1/2/3 (the third is my favorite, second is least)
Castlevania 1/2/3 (all fun, but I prefer the tightness of the first and the exploration of the second)
Zelda II (yep)
Panic Restaurant (very fun little platformer)
Monster In My Pocket (ditto, great Konami stuff)
Gimmick! (very, very technical)
Ufouria (much better than you'd think initially, very exploratory)
Adventure Island II/III/IV (the fourth is an exploratory platformer like
Monster World, great stuff)
Holy Diver (fun, but HARD)
Battletoads (ditto, although it mixes genres a lot)
Xexyz (not the greatest platforming, but an interesting and weird shooter/platformer hybrid)
A Nightmare on Elm Street (surprisingly decent, actually)
Mega Man 1/2/3/4/5/6 (duh)
Chip 'N' Dale 1/2 (first is better)
DuckTales 1/2 (I like the second better, personally)
Darkwing Duck (secret
Mega Man)
Tiny Toon Adventures (good hop 'n' bop)
Bucky O'Hare (I actually think this one's just okay, but worth a shot. Brutally difficult.)
Kid Icarus (inverted difficulty curve)
Metroid (a little rough, but still excellent)
Gremlins 2 (actually overhead view, but definitely platforming)
StarTropics 1/2 (ditto above, kinda qualifies)
Faxanadu (platforming is just "eh", but game is great)
Contra/Super C (duh)
Bonk's Adventure (surprisingly good port)
Little Nemo (I had a rough time with this one, but it's fun)
Blaster Master (Worthwhile exploratory platformer, mixed with overhead stuff but tank sections are best.)
Snake Rattle 'N' Roll (fun, but brutal and a tough isometric viewpoint)
G.I.Joe 1/2 (The first game is solid enough, I actually like the second a bit better)
Journey to Silius (great soundtrack)
Little Samson (rare as all get-outs, but great)
Bionic Commando (definitely in the top 10 platformers on the system, maybe top 5)
Kabuki Quantum Fighter (no, I'm serious)
Kickmaster (feels a bit like
G.I.Joe, I think same developer)
Splatterhouse: Wanpaku Graffiti (simple but fun)
Jackie Chan's Action Kung-FuKid DraculaWhomp 'EmFlintstones 1/2 (solid, pretty decent anyway)
I think I'll stop there. There's a lot in there I find really, really good, some are just solid, but there's a wealth of good platformers on the system.