Kirby Super Star is the best game in the series. Splitting it into different games was a brilliant move -- you can't say it's too short, yet it doesn't feel long and drawn out, and it also provides some variety as each game has its own feel. It is also a little on the more challenging side compared to some other Kirby games (although it's still not exactly difficult), and it's one of the more fast-paced entries in the series. Another great thing about it is that there are a larger number of different powers you can copy, and each power works in multiple ways (by dashing, holding a direction, etc.), which the game conveniently explains to you when you pause. The only thing it's lacking is the animal friends.
Kirby's Dream Land 3 felt like a step back. The animal friends are back (and there's more of them), but there are much fewer powers again. It's also a bit slower, although it's not as bad as Kirby 64 in this regard. It's easier in terms of direct action, but it does have some puzzle-based challenge. Still good, but not as good as Super Star.
Kirby's Dream Course isn't too great. It's basically Marble Madness meets billiards. On a series of obstacle courses, you have to hit all the targets and sink Kirby through the hole. Instead of moving Kirby around, you take turns aiming and shooting. It has its fans.
Kirby Star Stacker (Japan only) is a pretty basic puzzle game. Match the animals to each other and they'll disappear along with any star blocks that separate them. It's alright, but it's not exactly a top tier puzzle game. I'd much rather play Tetris... or Columns, or Klax, or Puyo Puyo, or Bust A Move, or Tetris Attack, or Baku Baku, or Magical Drop, or Puzzle Fighter, etc.