There are a lot of things that separate a good animator and a bad animator. I will skip the obvious things like talent, speed, good mechanics, fundamentals, etc. There are a lot of animators out there that have all of those qualities. I know for me, two things that inspire me are an animator's attention to detail and creativity. Of course, all shots have to tell the story, sell the emotion, have good body mechanics, timing, weight, etc. What is unfortunate is that a lot of times a shot will have all of those elements, and then the animator will consider it done. I've been guilty of it myself.
A good animator will work his shots until they are good enough to be in the film. A great animator will take it that extra 5 percent past what is required and make it amazing. Feet don't land square to the floor most of the time, and fingers don't grab an object and then stop moving. Eye lids are constantly reacting to what is happening in the eyes, and the face has so many ticks and tiny oddities that it is overwhelming. The animators that blow me away always seem to take the time to add the small imperfections that make a shot feel real. Sometimes there are small details that you feel more than you see. However, if they weren't there it wouldn't feel nearly as sweet.
The other thing that really gets me pumped about a shot is an acting choice that I would never have thought of. Some animators are able to come up with ways of expressing an emotion or an idea that are wildly original but seem to not be out of place for the character. It is very obvious in those moments that the animator put in the effort to avoid the cliches and brainstormed until they had something special.
So, I guess I could sum up my view of a good animator as someone who has all of the skills but also takes real pride in their work. They aren't just trying to get their shots approved by the director, and they aren't running with the first idea that will work. They are not just trying to get four seconds of footage into the film. They are trying to create four seconds of inspired animation that will help elevate the film. I've seen animators that have been in the industry for many, many years and still labor over their shots that way. I am hoping that I can end up being one of them even after I've been doing this for a few decades.