pg_dump format => custom vs sql
Time it and see. Which is fastest will depend on the balance of CPU to disk I/O on your system. If CPU is abundant and the disk is slow, a -Fc dump will be faster. If CPU is very limited and the disk is fast, an SQL dump might be faster.

I strongly recommend using -Fc custom format dumps anyway. They're much more flexible, and while you can convert a custom format dump into an SQL format dump you can't do the reverse easily.