I can't tell you which one, but as far as I know Deb has two templates and each one does several sizes.
The petite template will do- 5, 6, 7, and 8 inch blocks.
The large template will do- 7, 8, 9, and 10 inc blocks.
So I guess it depends on how big you want your stars and finished blocks to be, but know that either size will allow you to do 7 and 8 inch blocks.

I'm a spanking new quilter and tend to feel more comfortable with bigger everything as there is more wiggle room for mistakes, however I was able to use the petite template and got great results because of the built in wiggle room the template gives you . I can't wait to try the 8 inch blocks next.