Almost any side snapping dipe will pull on pretty easily, especially if there's elastic in the front and back. I used Mother Ease fitteds and liked them. They have an organic option.
Imse Vimse makes a good training pant, but it has a waterproof layer so you can't really double them up. I've also heard good things about Little Beetle, but they didn't fit my DS well. Which ones did you choose?