Our Take on it:
BigCommerce is a great solution not only for B2C businesses but has also been equally fruitful for B2B businesses or a combined one that targets both types of customers.
The first thing on your checklist should be SEO 301 redirect since that is the main key towards migration, if you don’t do that you will lose on search rankings that obviously no one would afford to do. The next thing on the list should be the migration of scripts or service integrations that you currently have with your store which could be your reviews system, Google Analytics, POS, Inventory Management solutions etc.
We believe that the two things mentioned above are of the utmost importance when taking on the migration of the store, and if you are able to achieve these things correctly the other stuff should be rather pretty easy.
Once the migration is done, do not forget to run a broken link checker tool on your website.
You can go through other recommendations here: BigCommerce Migration Experts RoundUp