All this discussion seems to ignore ( what I presume to be quite common knowledge) that while Conrads, Hiltons and Hilton Garden Inns were originally specifically designed niche lines within the Hilton portfolio.
The Doubletree, Embassy Suites and Hamptons lines were acquired by purchase (what? ten years ago??) consequently logic would suggest that would be a certain overlap in the type of lodgers and or areas thay might attract or attemt to serve.

That said IMHO ALL HGIs are much better the Holiday Inn Express line and most Four Points. They are also better than the great majority of Hamptons.
While there are (quite)a few decent Hamptons there a number of pretty awful ones.
With the HGIs being newer you know exactly what you are likely to get.

mike