My favorites are:
Tumblers - small and large one
2x2 sq for using up my scraps - leaders and enders
2.5x2.5 sq
Rag Dies both small and large one, the shape rag dies
Brick die 3.5x6.5
I have most dies ( no designer appliques tho- no interest) , and i can rotary cut strips faster so my strip dies hardly get used unless im using scraps.. then its just much easier to use the die..
I currently using my big 9in hex... I really like this die too..