Cirkuts are much more complex and a lot less were made. I believe they made many thousands of panorams. They made a total of 400 #5 cirkuts. The #10 was most common with around 1900 made in the 40 years(!) of production The #16 was rarest with around 100 made for the many years it was available. It doesn't matter much since they really do different things.
I've been shooting with al vistas and like the results. The 5" al vistas are common enough to find. The baby al vistas are more uncommon, but fun. I was able to snag a 7" x15" format al vista for a reasonable amount, and love the results I get (http://jamieyoungphoto.com/AlVista%20photos%201.html), though film is problematic. I haven't had much luck with my panorams yet, but will try again sometime.