Opinion, others will differ.

Carter W-1 (see link for discussion on these carbs):

http://www.thecarburetorshop.com/CarterChevroletW1.htm

The 1941~1948 models are some of my favorite carburetors.

Carter YF: As designed, an excellent carburetor. Major issues include (A) local FLAPS repair kits have wrong parts for Chevrolet YFs and (B) the neopreme (diaphragm) accelerator pump will have issues with ethanol-laced fuel on vehicles which are rarely driven.

Rochester B: ALL of them will warp and leak through the power valve, although the later design may last a little longer than the early. I personally had a 1959 Chevrolet Biscayne with 9,000 miles which my Dad bought for me in 1962 which got 12 1/2 miles per gallon because of this carb (later design - three years and major warpage). Yes, they can be straightened (and last another couple of years), but I have better things to do than straighten carb castings. Our shop will NOT rebuild these carburetors. If one likes the carb, the neopreme accelerator pumps in the FLAPS kits don't last over a couple of years, but leather accelerator pumps do come in the better kits. We have been trying to GIVE AWAY these units for years:

http://www.thecarburetorshop.com/Free_carbs.htm

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop