As posted above, something "wrong" (mold likes, gaps, paint runs, etc.) creates a quick negative impression that is hard to get past after. Assuming proper care and attention though you move on to what does get you excited.
I'm impressed with the skills of people that paint (for lack of proper terms) the 'evy Metal / GW way that I'm used to seeing on 40k and such models. I don't mean this in a negative way at all as it really does require significant brush control and paint modulation. Dead Marsh's Lurtz is a good example of this. Edge67 has elements as well such as the cloak on the victim and some of the details on Lurtz. These look great, but almost "too great".
But what I strive for in my own work and what catches my eye in others is when someone pulls off great detail while having a very natural (often considered 'dull' ) appearance on the model. Draked and S83 got this with their Lurtz entries IMO. I like to see a model that looks like a still image from the behind-the-scenes clips or as if you are viewing the real actor/character from an appropriate distance. Often this will mean little to no eye detail, for example, so when someone gets that "just right" balance of a hint of eye detail without making it obvious (and I don't even mean over-sized...just what many people do well for "display great" doesn't ring true to me for "realistic") it makes the face pop.
Look at these two for example for what I mean about faces with subtle eyes and muted but obvious details. I think the scale is appropriate. This "style" of appearance are what I strive for in models rather than the more typical GW styles. I'm not there yet, but life is a journey.
There are many other things, proper shade and highlight and an equal attention to skin, cloths, armor (sometimes people spend so much time on one or not nearly enough on another). The base is important and again here my personal tastes are not always in line with what the community as a whole tends toward. But even a great base isn't going to make up for issues with the model, but a very poorly executed or plain base can hurt your impression of the figure even if at a subconscious level.