Either one is a good unit. Compare the size of the primary bores on the Q-jet to the ones on the Edelbrock. I believe the Q-jet primaries are smaller than the Edelbrock's.
Your driving style will dictate whether the Q-jet will work better for you. If you drive conservatively and keep the secondarys from opening up all the time the Quad "should" give you better fuel mileage. If your "foot's into it" all the time stick with the Edelbrock. Just one opinion.
Quadrajet all the way!!! the best and most misunderstood carb of it's day.
The Edelbrock is a good carb but it's working the most efficient at a flow of 600cfm. Unless you have it mounted above a big block thats a lot of rpm to breathe 600 cfm thru a small block.
A quadrajet's metering, on the other hand is changed by engine demand so the same carb mounted on a six will do just fine on a 454
There is a pontiac dealer i believe in the dallas texas area that has tons of info on quadrajet tuning and if you want i could seach for the address. they had a good web site.