Installing Windows Server- Any thoughts or Experience on using Windows Server 2008r2 or Server 2016

I have an application that unfortunately requires Windows Server. I have an iMac which I have resigned myself to sacrificing for this task. Does anyone have any experience/thoughts/suggestion/advice/warnings/success or absolute horror stories about either platform (Windows Server 2008R2 vs Windows Server 2016 (standard installation)? Parallels/Windows Server XXXXX/and Patterson Eaglesoft 18.1 are the only programs that the Mac will be running (7/24) for about 3 months.....