I don't have a Blue Ridge, but I have a Ped. Pennsylvania flintlock, their Kentucky pistol, and three Howdah pistols, and I've owned a GPR in the past. The guns from both manufacturers have been good quality, no problems with any of them. The Ped. flinters have been very reliable over the years, fast ignition, easy to clean.
I think the choice is between apples and oranges. It would be easier if you were comparing a Ped. Penn rifle to a Blue Ridge, or a GPR to a Traditions Hawken. But I think a Blue Ridge and a GPR are too different in construction, style, feel, and everything else to really make that comparison. If it's just a matter of quality, my experiences have been good with both. Beyond that, you'll just have to decide which one you like best. If you like them both, the ultimate answer you'll find in the end is that you won't be happy until you own one of each. I'd just go with whichever one appeals to you more. If they appeal to you equally and you can't decide, flip a coin.
That's :2