i'm using google photos. it has free unlimited storage as long as you don't choose to save images in "original" quality, i.e. uncompressed.
free unlimited is pretty good but it does have 2 drawbacks:
- to use a link to an image in a post or otherwise publish it, you must add the picture(s) to an album. then open the album, open the picture from there and copy the link from there. using the URL for an image directly without doing it via the album, will create a dead link for anyone who is not logged into google. it's something to get used to.
- the URLs of the images are very long. doesn't really matter in most cases, but they they just aren't very handy.