My company has used Shipworks for almost a decade. It saves our shipper a lot of time since it pulls feed from Amazon and prefills all the shipment info into UPS Worldship. It works with a lot of other ecommerce platforms too but we've only used for Amazon and our website orders.

I like ShipWorks as it integrates and sorts all the orders that were placed from the website and it is easy to print the labels. Easy to use and user-friendly compared to others.

It just works! And support is excellent, even to just ask general shipping questions.