Well, I've always been partial to British Zenith updrafts myself ... NOT!
Seriously ... ASSUMING that you mean the "usual" 4-BBL aftermarket carbs ... I like Holleys.
There are a ton of them out there, parts are plentiful, and they are relatively simple to disassemble / re-assemble. I'd recommend one that has the dual inlet center-pivot float bowls, because the single-inlet with a transfer-tube style causes most folks a lot of stress.
On the other hand, though, most mechanics that I talk to seem to prefer Carter AVS or AFB carbs. I am considering one of Edelbrock's Thunder AVS (Carter Style) for my current project (Chevy 454 in a 1966 GMC).
http://www.edelbrock.com/automotive_...ess_main.shtml
I scares me a little to see that these are being built by Magnetti Macaroni
though. They were the guys that built some really odd-ball alternators on agricultural equipment, and I used to shudder a little every time some old farmer brought one in for testing / repair!
Don