After trying out many other well regarded solutions (Stitch Labs etc) we finally found our way to Skubana. It was recommended to us by several other high volume ($1M+) eComm shops, and so with a bit of trepidation we gave them a try. Best. Decision. Ever. We were on-boarded in a week, and fine tuned within our first month. We even were able to ditch our other shipping tool, ShipStation. Given that all of our systems are now in one, reporting is much easier.
The support team there has been top notch, and very responsive. Great work guys. You've earned our loyalty.