I like wendy's out of those. but my favorite are local places. my alltime is the GIANT in Lake Oswego Oregon, that place is just outside of portland. if you are ever in the area, you MUST go there. the are soooo good.
Now I just realized they may be out of business, but I doubt it concidering how many customers they have, but weird things can happen over time
my favorite chain is burgerville. I think it is a northwest thing, but they are good and actually fairly HEALTHY, hot damn