The bug free for all ones or the butterfly catching one are my personal favorites because they're easy and I can pick flowers to take home without wasting pocket space.
My favourite tour(s) on the island would either have to be the hammer tour or the balloon tour. Hitting the lawn mower and popping balloons are so satisfying for me personally, and I honestly find these two tours relaxing even though they are meant to be the complete opposite. I find it so easy to unwind because of how easy I find the balloon tour to be, and how easy it is to get medals from it. It's an easy way to get medals if you ask me, and the hammer tour is just a lot of fun.