So I haven't read all of the posts but I'll give my take on the easiest way to transfer photos from an iPad to an iMac.
Make sure both iMac and iPad have the latest OS/iOS and Photos app is on both the iMac and iPad. ( they usually comes preloaded from apple)

Start iMac>launch Photos> plug the iPad > on the left side of the Photos screen find the name of the iPad under devices>click on iPad name>at the top right of the screen click the import all new items.

Wait for process to finish. Length of time depends on the number of photos to be imported. When the process is completed, you can click on the Photos icon on the top left of the Photos screen and you should be able to find your photos.

I've done both ways, but I still find that PhotoSync is faster. Don't ask me why unless it's because the program is bypassing some OS Photos commands. But PhotoSync is quicker the times that I compared. But I'm glad that you found an easy way for you. Your method does work seamlessly too. Take care....

As a permanent process, you can set up iTunes to automatically launch the Photos app every time you plug the iPad into the iMac.
This is the quickest way without having to use iCloud, external or third party apps.