I recently had my mezuzas checked and they were all kosher. However, on the report it said that most of them were in the Beis Yosef font and one was in Ari zal font.
As an Ashkenazi is it ok to use them if they are different fonts?
If you own the house (i.e. not renting), you should anyways try to use only Bais Yosef font since you are Ashkenazi.
All the best
Chazzon Ish was stringent, and that is the custom. C.f. Noda Beyehuda Y:D chelek 1 siman 80, and Y:D chelek 2 171 who writes that Ashkenazim can use Arizal and Vellish (sfardi) font.