Yoshi's Island, definitely the best Yoshi game ever made and one of the best 2D platformers.
Kudos for including Yoshi's Cookie on that list, I voted for that too. Good gameplay, has Yoshi in it, cinema scenes after each round which are incentive to keep playing, lots of Mario cameos and backgrounds, and the title screen music. That music is one of the best I've ever heard. Something about it and the intro always gets to me emotionally.