There is never a simple answer. I own an HP-1, BCD396XT, GRE PSR-800, and more. All have there good and bad points. It really depends on how you intend to use it and what you want/need in a radio/scanner.
The biggest feature from the 396XT I miss in the HP-1 is Close-Call.
I find the audio in the HP-1 to be superior (I've had multiple problems with the speaker in the 396XT).
The larger screen and more descriptive text options in the HP-1 are better for my old eyes.
The HP-1 far outstrips any scanner for mobile scanning while travelling with a GPS. I've traveled many thousand miles across the country with the HP-1 and it has always been a great (accept for the period when the GPS port broke and required a Uniden repair).
While you can use the 396XT (and other Uniden scanners) with Location Based scanning (including real-time GPS update), it requires a great deal of effort to set up initially and keep updated. The HP-1 Location Based scanning requires very little effort to setup, and the weekly updates are great.
The HP-1 weekly updates do rely on the accuracy of the data in the RRDB, so it's important to support RadioReference and the many volunteer administrators. You are nor restricted to the data from the RRDB, the HP-1 allows you to create custom user Favorites Lists which can be set up in just about anyway you desire, with data from any source.
So I'd recommend the HP-1.
Ted