[RMcNeal]

I have the 3791RD, 2019 Anniversary Edition Legacy. I really love the floor plan. I haven't looked at the 377FL, or any High Country models really, so I can't speak to those. We tend to load based on where we are going and what we are doing on the trip. Some things like the grill, tools, etc. go all the time. Others like the portable canopy, beach/fishing cart, etc. only go on trips where they will be useful.
We tend to travel 4-5 hours a day at most and plan trips accordingly. Usually our last stop on the way home, I pack everything from the inside in the garage for easy access once home, since I can't open all the slides at my house. We usually do all our cleaning on the last stop as well so the rig is ready for the next trip.
The pull out garage tray was the main selling point of this model for us. Most of the Montana models with rear living have similar floor plans. We do like have two pull out queen beds in the rear den, but it wasn't a deal breaker. The pantry is huge. I can see where it wouldn't seem so if we were living in it full time as we have become accustomed to the large pantry/laundry room in our S&B, but for an RV, it's as big as I have seen in any model.
I have been told that the Montana models have higher quality materials than the High Country models and a price point that reflects that as well. Don't want to start something as I haven't compared and have no personal experience with the high country.
All that to say we love our 3791RD and wouldn't trade for any model or brand we have seen since. YMMV. Good luck with whatever you choose.