The best theme for Beaver Builder… if Beaver Builder is at the centre of all you do. Clean, simple and extendable. If you want 100% compatibility,integration and support use this. If you at developer you will like how well coded and logical it is.
If you want cheaper and don’t mind the risk that comes with buying a theme from a one person business without a recurring income model… try GeneratePress. It’s an excellent theme with a supportive author and works 99% well with Beaver Builder.
If Beaver Builder is not at the centre of your work Genesis is the most used theme on the net. Popular for making it easy to do code and develop your own child themes. Also for it stability. It comes with a learning curve and needs a 3rd party plugin to get full-width.