Migration Tools (specifically ShareGate and AvePoint)

I've only ever used ShareGate for this type of migration, and while it is faster than manually moving everything over one by one, you'll need to be aware that any little change in environments can often result in you having to go through each Form / Workflow anyways, in order to make sure that it's committed and working. 

In my case I believe I had made a duplicate of the site first (manually, but with all of the same columns / setup), and tried to then port over some Nintex stuffs from a Test server to a Production Server only to have it think that certain columns were not there / missing. 

I later found that it would have been a better idea to just port over the entire Site / List / Library whole-cloth from the Test to the Production using ShareGate, but you live and learn :) 

Beyond that though, I have found sharegate to be an extremely useful tool in just managing several sharepoints at once. Especially if you have multiple versions and information that is stored in one place, but not another. It makes moving data between servers an absolute BREEZE, and using the mapping tools you can do nice stuff like automatically fill in data that would otherwise be missing (like if a person is no longer with the company and therefore no longer in AD. You can default instances where a person isn't found with a new user). 

Ditto