The best thing about the Pikmin series as a whole is that each game brings something very new to the table and feels so different
Pikmin 1 is a bit intimidating because of the foreign setting and the race against time, which makes it so cool.
Pikmin 2 is all about the hardcore cave fighting and those 2 hour-long treks into some of the most insanely challenging dungeons ever. Really immerses you in the game. Plus that final boss was so difficult
Pikmin 3 is about exploration and discovery, finding the new pikmin types, finding fruit, solving puzzles, being efficient, and has a lot less combat compared to Pikmin 2. However, the bosses were all INSANELY awesome! They felt like real challenges that required wits and skill, and I loved them. Also, the final stage is extremely well-made, really felt like a true final challenge, as it was much more than just a boss.