I posted some reviews, direct comparisons and a lot photos of sowbellies from different brands. They should come up with a search.
In my opinion...
The construction and mechanics are most consistent on the sowbellies from Case. Very high riding sheepfoot but it can be dropped by grinding down the kick.
The Moore Makers (Queen) are closest patterns to the antique 90 year old sowbelly knives from Remington and others. Some of them are built well and some of them are terrible. Good grinds (rare for Queen) and good 1095 steel.
Some of the old Queen-made Winchesters from the late 80s are built pretty well. Good grinds and good 1095 steel.
I'm not a fan of the 420HC steel or the grinds on the keystone series Schatt & Morgan knives. There's a F&W Schatt & Morgn with ATS-34. Good steel. The grinds aren't the best though. And build quality of the S&M knives is hit or miss.
RR and Colt are cheap. The spey blades always rub the liners but mechanics are usually pretty good. Lower quality materials. I'm not a fan of their steel but others like it. In my opinion, most of the handle materials look like they belong in the dog chew toy bulk bin at a pet store. Others like them. Opinions vary. The black and white bone stag is actually really nice though--at least, I like it a lot. I don't like the shape of the clip blade on the 3-blade but the clip blade on the 5-blade is the perfect shape. It's much more full. I don't know why they just didn't use the same blade on both knives. I've thought about converting some 5-blades into 3-blades.
Some of the old bulldog knives have carbon steel and pretty good fit and finish. I don't like the deep blade etches at all. I don't have any experience with the new ones.
I'd love for GEC to make a sowbelly that closely follows the old Remington pattern. I've been begging for years. One year it was almost the forum knife but my campaigning wasn't effective enough.
The 3-blade is on the left and the 5-blade is on the right in this photo.