For small B2B sites, you can refer to our Magento 2 B2B Basic Package. It includes must-have functions for an online B2B site.
Meanwhile, Pro Plan would be a better choice for B2B sites that arise some advanced demands related to order and sales management.
For medium to large sites, Premium version of B2B extension Magento 2 is highly recommended. It covers everything you need to grow a wholesale business from A to Z.
If you're functioning in a special industry and don't need some features in our two plans above, or you have integrated the same features from other providers, Pay as you go will be a good choice.