I would like to get some different perspectives on this.
We currently use SharePoint 2013. This was installed about 3 years ago by a vendor. I think it may have been their first install because we have seen several things that were not set up correctly. We have had some weird issues, anomalies and things not working correctly  from time to time. So my thought is rather than upgrade to 2016, we stand up a new farm on new servers for 2016. What are the pro’s and con’s?  What does this involve? Are there any third party tools that we could use to transfer content from  SharePoint 2013 to SharePoint 2016?
I have done many migrations and would rather stay away from 3rd party tools unless absolutely required. ShareGate is my only preferred choice (not because I endorse them for anything in return because it is the best cost effective tool in any migration project as such).
You should simply setup a SP 2016 farm and follow the clean up advice from Nick above (Golden advice do not ignore it). Try to migrate everything first via content detach and attach method – if you have less content and can migrate over a weekend. If you need gradual move for certain sites then using a tool might be better – also – in scenarios where you need to restructure content in target.
One more advice – test test and test again. Do not go live with first testing and doing a dry run with business to see if there are any issues at all.
Regards,
Jasjit
