Avalara seems to be the "go-to" third party for sales tax integration with NetSuite, but has anyone integrated with Sovos or Thomson Reuters ONESOURCE?

We are installing ONESOURCE now. It is going very well. Very pleased with the team so far. As @C_Billings said it’s better with SuiteTax so we had to upgrade to SuiteTax AND install ONESOURCE at the same time but overall it been great

Suitetax is fine. I know because I was part of the team that built the integration. God help you with Legacy tax. I have three open cases