KatarinaGrumy

Below, I list some examples of the best Magento 2 extensions for an e-commerce website:

Accounting and finance — AvaTax, Sales Tax Automation, Connect Xero.

Customer support extensions — Live Chat, Help Desk Ultimate.

Payment and security — Smart One Step Checkout, Magento Two Factor Authentication, Sage Pay & Subscriptions.

Shipping and Fulfillment — Print Order PDF, Order Eraser, Custom Srock Status.

Marketing Extensions — Abandoned Cart Email, M2E Pro Amazon & eBay Integration.

If you need to hire Magento developers, you can go to Clutch or search via Google.

I think that there is no "the best web development company". It's subjective opinion of developers and business owners that interact with this or that company.
Here I'd like to recommend Whidegroup company. It is a cross-functional e-commerce development team with 10+ years of experience in the industry. We have helped hundreds of brands launch and improve their online commerce websites. They specialize in Shopify and Magento, website and custom extension development.