Could be independent integration or a bundle. Really just wondering if anyone has experience with either vendor and what it is like working with their software/services.

I worked with a company who used TR a few years ago. It was a nightmare integration and it felt like much of what should have worked out of the box had to be customized. But they did the work and ultimately (with a lot of delays and showing them where their calculations were wrong) got everything working as expected. The client said in hindsight they would have gone with Avalara.

For TR the software is fine. The integration they sell is a mess. Avalara isnt known for their support in the NetSuite space but like the others they too have an engine. The engines (TR, Avalara Vertex, Sovos, TaxJar) all have the same content. Its not like tax laws are secrets. Most of the engines also calculate the same way. If you were shooting for hybrid I would use a service but build the integration myself.