AVS vs AFB

The Poison Dart came with an AVS on a 340 intake manifold the engine appeared to run nice with the exception of a small miss nothing a tuneup couldn't fix, but the carb is really kind of scummy on the outside and they are generally a simple carb to rebuild, but I have several AFB's sitting around and 2 that are 600 cfm whihc will work fine on pretty much any small block.
So my question is whats your preference and why AVS or AFB?

Thanks again your input is always appreciated