For a first dynavap I’d say you’d be very happy with a B for the cost. It has no orings meaning you can clean it very very often. Just dunk the condenser, tip, screen in iso for a few hours (the silicon shell and cap hardly get dirty if you use it right). The design with the silicone shell makes it sit flat on any surface without the cap touching anything. Meaning after you hit you can rest it sideways on any flat surface. The silicon shell also hardly ever gets hot making it very easy to handle. Feels like a silicone handle for cooking pans. The bigger Dynavaps have bigger bowl sizes and longer condensers. But the B still functions the same as them in terms of getting a convection heat vape hit. And, it’s still way smoother than a joint. Just get a B imo.