Read and then re-read what Bjorn said about "get the carb you or someone else can work on". No aftermarket carburetor is perfect out of the box (although the Carter TQ comes close).

The brand of carburetor is less important than the design (square-bore or spread-bore). There is an excellent reason that ALL US manufacturers started using the more expensive spread-bore designs on virtually ALL production cars after the design came out; and that is because the spread-bore is best for the street.

As a general rule, the spread-bore is going to have much smoother driveability, and use less gas than the square-bore.

Remember that Pontiac used the Q-jet (spread-bore) on engines from the 6 cylinder Sprint to the RA IV.

Now, if you happen to be professionally road racing, the square bore is easier to modify for this purpose; probably also somewhat easier to modify for circle track racing. Drag racing no benefit (assuming equal CFM) either way.

Parts are probably more readily available LOCALLY for the Holleys. Mail order, probably little difference.

Jon.