They each have their place and following.
Long ago I had a truck with a 'self rebuilt' Q-jet and it got good mileage but the power wasn't there like I thought it SHOULD be.
Did some horse tradin and acquired a bright and shiny Holley. Spent about 30 on adapters/gaskets and linkage stuff, but It was like a new engine!! BUT
I only got about 10mpg and don't have a backfire. It will blow out the power valve. I've never heard (personally) of a Holley on a mild performance engine that got GREAT mileage..
I had a 66 Impalla with a self built 350/th350/3.31 gears with a Carter/Edelbrock 600 on it that got 19-25mpg with a 284/284 Summit bracketmaster. (...should've never sold that car) Just think if I had a 260 or something!
BUT, after reading Cliff's book, I saw where all the trash can get stuck in the Q if it's not cleaned PROPERLY. And all the other adjustments that HAVE to be addressed for them to run like from the factory.
You gotta remember that when peeps start to 'adjust' a carb, it's usually NOT in the right sequence. (Have you ever seen used carbs that have pound marks on top near the float bowl? ..that's right, tuning with a HAMMER
I've even ran into a off idle stumble that i would have sworn it was the carb, Messed with it and still stumble.. Ended up to be the distributor. NOW, I had to go back, set the timing/advance THEN go back to the carb and re-adjust it.
The primary's are tiny for good economy and the 1 7/8" secondarys can really launch from a stop or to a passing gear.
Hope you get to figure it out, but it can be frustrating also.