I would stick to the genuine Dellorto or a Bing as tuning parts are easy to find for both. I have recently tried a Dellorto 14.12 SHA on my bike but I didn't have a main jet on hand that was small enough to get it running right (it had a 58 but probably needs to be around 52).
I'm sure you could find a used moped carb cheap. The Dellorto 14.12 SHA was used on Tomos and the Bing was used on Puch.
Here is a good source
for new carbs and parts.