I worked with both Installshield and NSIS and vastly prefered the latter, it just got the job done.

I used to do the CodeWarrior installer for Freescale/NXP embedded product lines in the 2010s and InstallShield became completely unworkable as a tool for a massive dev tool. Even today, a 400MB+ installer is difficult, let alone in the age of mechanical HDDs.

I had to choose between NSIS and Wix - and while native installer formats were clearly the future even back then, the performance and compression advantages of NSIS were so great that it was a clear choice. Solid LZMA was simply impossible to beat by any deflate/zlib/mszip oriented tool.

The joy of the dev team was palpable, the new installer was about 60% smaller and installed in one third the time.

I did installer stuff for about ~10 years, mostly InstallShield, deep in the weeds with Windows Installer table editing and custom actions, and making the InstallScript engine do things it wasn't designed for.

These days, I would personally use NSIS for small stuff. Wix installer for anything bigger/more enterprisey. Last I checked SharpDevelop's WYSIWYG editor was pretty decent for Wix dialogs.