I like
Susan.
I prefer the variant
Suzan - I guess because
Susan looks like it could be pronounced with two S sounds and I don't like that at all.
I also like
Suzanne.
The forms that end in -a / -ah don't float my boat.
Susannah is too stuffy and
Suzanna seems like a smush with
Anna.
I like
Sue more than
Suze or
Susie.
Suki /
Sukie could also work.
- mirfak