Well, Barry Grant is out of business now. That should narrow the choices down.
I've never had a Demon carb that was built correctly out of the box. They have all needed rebuilds, cleaned, or modified in one way or the other. One of the reasons that BG went out of business is just because their QC went downhill. Tons of trash in the carbs, screws left out, etc, etc.
You will not go wrong with a Quick Fuel. I use them on every engine I build for a customer. They are a little pricy, but you get what you pay for.