Ok that's actually a very hard question!
1. Adhesive--I love my ATG, prior to that I used the square adhesives which took forever to place all over my pages!
2. Glass mat
3. Die cutting machines -- sadly I have more than I can use! I have the original cricut & cricut expression, Slice, Cuttlebug, and now the Grand Caliber!
My favorite lines are Bo Bunny, Little Yellow Bicycle, and Graphic 45.