Recently stayed at the Hampton in Vacaville CA. This was the nicest Hampton I have ever stayed at! I hated to leave. That being said, I have found many decent HI and some pretty crappy ones.
I really enjoy the HGI brand. I find the hotels very consistent in terms of service and amenities. With HI, it can sometimes be a crapshoot. At HGI, you always know exactly what to expect.