It's hard to argue with a large sample and uniform testing.
My only experience with Bula Barrels is looking at others'. I wanted a UHBAR, but at the time of the decision, Bula wasn't producing them (and so far as I know still isn't), so between TonyBen's recommended options, I leaned on the Krieger, and that's where that's going, and so be it!
As far as looking at other's experiences, those who witnessed bad samples, at least of those I've read, were in the very beginning, and had to do with cutting of the chamber. It also coincided with James River Armory building a lot of them, and for too cheap to probably be sustainable. The picture that paints for me, which can fit into your experience, is that the great majority of reported issues could have been related to not the manufacturing of the barrels themselves, but in hasty assembly, rushed finish reaming to set headspace, and a lack of QC, largely on the part of James River Armory, who was getting a complete M14 type rifle out the door, built with largely forged parts, for close to if not the cost of what Fulton Armory sells a partial USGI parts kit (not on sale) that doesn't even include the stock, barrel, or receiver. Clearly, a nice idea that was fundamentally impossible to execute well.
There very well could have been initial manufacturing issues regarding the barrel itself, which is somewhat to be expected in that there is a learning curve in all things, but I haven't heard anything related to that significantly after the beginning of production, and that you've bought a fair number of them, over a long period, and have wrung them out... I think that means a lot. Plus, I've not heard a single story of Bula refusing to fix something that had a verified performance problem, which speaks to something the buyer of any product should do, test drive the heck out of it. If you want to know how well it shoots, or more importantly, how well it shoots for you, go shoot it.
If you're buying it for what it's supposed to be able to do based on what other similar rifles have done for somebody else, or reputation, will shoot some groups until you get a good one, remember that group as 'how it shoots', and then throw it in a safe for eternity, that's fine too, and I honestly think there's absolutely nothing wrong with that, but it's also a different set of criteria.
If we actually
want to know how anything performs, especially for us individually
valid way of knowing is to bite on something, put the time in, and see how it goes, and understand that there is always the risk of making the wrong decision, or just getting a random variation of unknowns that for reasons of Lazerus 2000's 'M14 Voodoo' make one rifle work better than another. If you get the 'another less betta', you can futz around with it until it's doing what you want, send it to somebody else with perhaps more expertise to futz, or just punt, sell it or part it out, and buy another rifle, either the same combination, or a different one, and repeat until you get what you want.
Maybe that's not an attractive combination, in which case maybe paying more to somebody to build it who will give you an accuracy guarantee, and will put in the time to test and adjust it and do the futzing on the front end, becomes a lot more attractive.
Of course, part of the equation is the shooter, and in that case, you're stuck with what you've got, for better or worse.