For an email signature, what is the “ideal” CDN image hosting provider? [closed]

Email signatures typically have an image of a logo or a profile picture. My question is, what is your recommended image hosting URL/service? Are some URL’s trusted over others?

I am not sure where to host these images hence the question.

I guess some ISP’s and email clients determine the "trustworthiness" of an image URL?

All experience greatly appreciated!