If you just want the pan for cooking - either are great.
For collectibility Grizwold are generally more collectiable, and worth more money. Wagners can be inexpensive or expensive depending on many factors. I own a couple of books on the subject; used to use them to aid in my collecting. You can find more information here:
http://www.griswoldandwagner.com/cgi-bin/yabb/YaBB.pl