We see thousands of images.
Even for an artist we like (and could instantly identify if we saw a picture by them), we have favourite images. And from the artists view point - even the greats have moments of grace - special works.
We can appraise an image pretty quickl - it's all there in front of us, the eye is fast.
But when I ask myself, "How many paintings by artist x (hey, let's say Soralla) can I bring up in my mind?", it can be surprising how few (if any!)
A great image (on a personal level) is, I feel, one that stays forever in your mind.
(see my comments on those 2 Michel De Gallard paintings I've loved so much - because they have a particular meaning for me (induce a dream-like trance!), for one thing and I love the paint surface, for another. Like I said above, once we go past the critical bit - get to lave a painting - it's special to us - well, another one I like is Bryce Cameron Liston's 'In the Stillness' he entered it in the last ARC competition - you can see it e.g. on their site in the entries for the competition)