This is just a made scenario lets say more than a million daily, but putting a number would be hard. But lets assume total image views would be around 100k

This is just a made scenario lets say more than a million daily, but putting a number would be hard. But lets assume total image views would be around 100k typically an image of 1-2.5 Mb compressed with a ratio of 60% it's pretty important to serve the image. so, reliability would be important. it should be cost effective. The images will be stored for a long while.