Any format that has licencing encumbrances will never be fully supported, so is a bad choice for archives, IMHO.
Any lossy format is also a bad choice for archives.
Technically, I like the successors to JPEG, but they lack support.
I think you should choose a lossless format that is currently widely supported. So that would be TIFF or, arguably, PNG. Sure, the compression for photos isn’t great. If you don’t need metadata, PNM is a good choice: dead simple, so a program to read PNM can be written in a couple of minutes.
You (or someone) will also be considering the physical media, and will probably conclude that they need refreshing every few years. When that is done, consideration should be made about also changing the file format.