I've only tried Morton's and Ruth's Chris from that list. Given those two choices, I'd pick Morton's, but I've found their steaks to be kind of hit or miss.
I prefer Magnum's signature steak (a wonderful ribeye) to everything else I've tried. I'd put Gibson's above Morton's (they're across the street from each other in Chicago).
Note that this is based solely on steak taste - I don't really care about decor or service (unless it's really atrocious), and I don't really remember much about appetizers (except the Lobster bisque at Morton's was terrible).