LogFAQs > #972425480

breaking down the Kirby games a bit:
KDL: it's the shortest, but Kirby doesn't have his copy ability yet
Adventure: introduced the copy ability, but it's kind of basic
KDL2: Introduced animal buddies, so copy abilities are different depending on which buddy you have or if Kirby is alone. Unlocking the true last boss can be a little annoying.
Super Star: actually six smaller games that only take a few hours each tops (and also includes a loose remake of KDL1). Gets rid of animal buddies, but instead of each copy power only having one ability, each one has a moveset so you have charge attacks and different attacks if you're jumping or dashing. Also has co op, with Kirby giving up his copy power to summon a helper that can be controlled by a second player or the computer.
KDL3: brings back animal buddies, but gets rid of copy ability movesets so it's more like KDL2. The true last boss is a bit more obnoxious to unlock, since each stage has a secret mission.
Avalanche: Actually a reskinned Puyo Puyo 1. It's probably better to just play Puyo Puyo 2 instead since it's more balanced (there's no way to counter and send back garbage blocks in Puyo Puyo 1, so whichever side that creates an orange symbol worth of garbage blocks first basically wins every time)
Dream Course: Minigolf, with copy powers and some other gimmicks. Seems a bit tough though.

Kirby Super Star is probably the best overall one.

as far as other games go. Mario Land 2 is decent. Wario Land 3 is one of the weaker Wario games and pretty much just a worse version of Wario Land 2, but some people like it anyway (the main problem I'd say is that there's a lot of padding which puts a damper on the excitement of treasure hunting, you have to collect a lot of treasures that just exist to unlock other stages or make other treasure chests reachable or even get back to Wario's basic move set from 2 instead of getting actual new abilities) and platformers where you don't die are pretty rare anyway.

As far as puzzle games go, Puyo Puyo 2 and Panel de Pon are among the best falling block style games, and Magical Drop 2 is decent enough to play for a bit. I like Wario's Woods, but it kind of runs the concept into the ground with too many rounds and not a lot of variety between them so it might be skippable if you are trying to get the most out of your time. For more structured puzzle games where there's levels with a distinct solution, I would say that Adventures of Lolo and Fire 'n Ice are both worth looking at (and aren't too difficult for casual players to finish without looking anything up).

Vice: Project Doom and S.C.A.T. are kind of niche/cult classics although I haven't really had time to play them yet.

edit: of course people already brought up most of the points I was going to make about Kirby while I was typing lol