you have the original (a pic of my lovely daughter) and then a 100% crop of the eye revealing the compression rates for Baseline (which would be the absolute minimum amount of compression you can expect from a JPEG), Optimized set to 12, and Optimized set to 2.
I bypassed the Progressive option because it's just not really used much these days. It had it's place when the fastest connection out there was a 56k modem and you had to wait minutes for a page of images to load, but these days it's irrelevant (IMHO) and I'm not really even sure why Adobe continues to have it as an option.
At the end of the day - always choose Baseline Standard at the highest setting (12). In lieu of being able to provide compression-free TIFF files, it's the best option.
ETA: Also, in case you didn't know - Photoshop RECOMPRESSES JPEG's each time you save them, compounding the amount of compression visible each generation. Think of it like a Xerox where you scan a document and then later make a copy of that scan and then make a copy of that copy ad infinitum. You end up with a garbled mess eventually. This means if you have a rejection and you need to go back and rework an image - do it from the original TIFF and resave a new JPEG from that instead of making changes to the JPEG. Even saving at Baseline Standard will degrade the image quality over the course of 2+ generations.