scanning old photos

I am scanning old family photos, planning to save them and give to family members for Christmas. Here are my questions:
1. How to save the file to a disk that can be read on either Mac or PC?
2. Use disk or flash drive? The flash drive would be readable by either type of computer,
but I notice commercial services offer saving to disk only, so there may be a reason?

Thanks to anyone who has good suggestions.

Use the jpeg file format and put them on a USB flash drive (most are formatted to FAT 32 which is readable on Mac and PC

Alos make a DVD backup, OSX creates dual format PC-Mac disk by default