I haven't really extensively driven either, but I have test driven them so I have some experience. I also drive an Insight, which should function similar to HCH, although not identically.

Just based on that I would be highly inclined to go with the HCH. The Prius is cool in that it can run on all electric mode, but that's all it has going for it in my opinion. The central screen showing what the car is doing is very poorly placed and I would consider it both an inconvenience to use while driving, and also a downright hazard. In order to get good FE it helps to be able to see what is going on at all times, therefore the FE gauge should be right in front of the driver at all times.