I use Prenax, they are not on your list. They are very responsive, issues resolved quickly, customer service is exemplary, claims are easy to do, and they resolve them if necessary. Check them out.
Oh, and good luck.

Mina Davenport, Librarian
Childrens Hospital
Health Sciences Library
747 52nd Street
Oakland CA 94609  USA
(510) 428-3448 (p)
(510) 601-3963 (f)
mdavenport@mail.cho.org