I actually agree with all posters on this thread.
I have seen instances (Pensacola Florida is a very good example), of the Hampton Inn and the Hilton Garden Inn being located side by side. While I have found the restaurant to be a little nicer at the HGI, the other differences in the hotels are neglible.
On the other hand, I have stayed in some crappy Hampton Inns (Foley, Alabama) and the Hilton Garden Inn 15 miles down the road at Orange Beach is absolutely great.