If you want the pictures small in disk size, make normal JPG then reduce the JPG quality at 50%. If not small enough, resize smaller the number of pixels then save them as JPG at 50% quality. For this I used to use GIMP.
After a while, made a small script function instead of manually editing with GIMP, called the function "webify" and add it to the ~/.bashrc file. It is using a standard tool called "convert", the main line is this:
convert PICTnnnn.JPG -strip -matte -resize 1024 -quality 50% -sampling-factor "2x2, 1x1, 1x1" PICTnnnn_s.jpg
At width 1024 as I use for casual posting close-up of electronics, the size is somewhere between 50kB-100kB, sometimes less.
Sure, all other options you listed are valid and can be used here, each with their own pros/cons. This sticky topic in the "General Technical Chat" section was also about making/posting pics:
https://www.eevblog.com/forum/chat/how-to-make-decent-photographs-for-forum-postsarticlespublications/