My go to cartridge is actually Plantin School Book that came with my Expression. I also use Story Book, Calligraphy Collection and Street Signs for lettering.
I have one of the older Expressions, when it stops working, I'll invest either in another Expression, the E-2 or whatever is on sale for Black Friday (if the machine dies around that time). I do want something large like the Expression, because I like cutting larger images for bulletin boards and such.
Hope this helps