Hmm... well, two are obvious.
1. Dracula X - By far the best platformer on the system.
On the list - Bonk's Adventure - A good fun platformer.
Beyond that though, I'm not sure. The TG16/CD doesn't have the wealth of platformers that the SNES and Genesis do -- there are fewer on the system, and the ones it does have are much more likely to be more dated, '80s-esque designs. I love platformers, so this is one of the bigger problems I have with the TG16 and CD -- I wish it, the CD system particularly, had more platformers! And of what it has... sorry, but I find the Valis games way too annoying to put on any kind of "good games" list, and I've never been a fan of Prince of Persia and the like (Fiend Hunter is a lot like PoP, of course). There's just not much else on the CD; the best other CD platformers I can think of are Jim Power, Monster Lair (if you count it as a platformer and not a shmup), and maybe Fausette Amour, though that one's kind of average. Of course Bonk 3 CD is good as well. There are some good side-scrolling action-RPGs (yeah, it is a category), though, if you include those -- Dynastic Hero, Blood Gear, and Exile are pretty good. But that really is a separate category.
As for HuCards, after Bonk's Adventure, what are other HuCard platformers I like... well, Shockman for sure is pretty good. I also like the first one, Shubininman 1. JJ & Jeff is actually decently good too, and Jackie Chan. Bonk's Revenge and Son Son II are good games as well. Liquid Kids looks pretty cool too, but I need to play it more. Also, yeah, it's not great and would not be in any top 5, but I do kind of like Energy -- it has that classic PC platformer style, a lot like the Western PC platformers I grew up with in the early '90s (since I had a computer before any consoles). Oh, and Dragon's Curse is good for sure, if you include action-RPGs. And... hmm, is Bikkuriman World a side-scrolling action-RPG, or an action-platformer? It is the first Monster World game, but it has a much simpler and more straightforward style than its sequels... I guess I'd call it an action-RPG, but it's closer than the sequels for sure. And the game is definitely good; I like the Monster World series a lot, despite not particularly enjoying either the original Wonder Boy or its Adventure Island spinoff series. And yeah, as the list below shows, I really like Monster Lair, while disliking most Adventure Island games... they are kind of similar, but just different enough for me to have very different reactions to them.
So uh, a list... I won't include side-scrolling action-RPGs, because those really are a separate thing, even if there is a lot of overlap.
1. Dracula X
2. Bonk's Adventure
3. Shockman
4. Monster Lair (though it's probably more shmup than platformer)
5. Son Son II
... I don't know, ask me again and I'd probably make a different list, but that one's okay for the moment I guess.
