I live in Fukuoka. And Welcome to Japan.
I have experience which stayed at GH and HR. I like GH. But I think HR is more convenient than GH.

If you stay at HR, you can walk and can go to the Hakata station.
I like the lounge of GH. Service is excellent.

If you are GP-Diamond, I think upgrade is decided at the time of booking.

thanks,
masahiro