Pikmin is such a formative piece of media to me and picking a fave is impossible for me. I love all the games so dearly! Pikmin 1 had this desolate and lonely kinda vibe, you’re on this unknown planet all by yourself with these peculiar alien creatures and environments, while Pikmin 2’s difficulty and addition of procedurally generated cave systems was a welcome challenge. Pikmin 3’s graphical style was pure eyecandy with all the textures, and having 3 captains meant a greater opportunity for optimisation strats. Pikmin 4 was like a successor to Pikmin 2 in pretty much every way, though I’d love to see the addition of enhanced difficulty sometime in the future!
My wife and I loved the co-op mode for 3 and were sad when 4 didn’t have it. That being said, we were pleasantly surprised with the amount and diversity of content that 4 offered and just finished getting 100% in it. The story was a little meh but the rest of the game was pretty enjoyable.