I prefer to see different art and animation styles, and I'll probably like it if it's obscure and original. While a deliberate "simple" style can be pretty cool, I think detailed drawings are in general much more attractive than the typical simple styles made with a regular to low budget funding.
I loved the art style in "Kaiba" for instance, which is what I'd extremely simplistic and (I think) low-budget. They had very few people working on it, if I recall. I also tend to like some well made short animations I also like SHAFT sometimes, like "Maria†Holic" and "Bakemonogatari." I'm not sure if they're very low-budget, but I'd also call them simplistic.
As for more detailed anime, I'd say "Mushishi" and "Byousoku 5cm" portrays things nicely. While I'm not the biggest fan of the style in "xxxHOLiC," I'd say that's pretty cool as well. Also, while I don't particularly like the typical Visual Art's/KEY style, I like it better than most other typical anime styles.
What I especially dislike is when a show uses static textures for clothes. I think SHAFT does this, e.g. in their version of "Negima!?," and I cringe whenever I see it. If you have no idea of what I'm talking about, it's when they for example place a pattern to colour an object, and when the object moves the pattern appears to be standing still.
I also dislike it when characters and objects that are animated don't match the shade of the background. I think this is a lot more common in American cartoon series than anime, however.
PS! Sorry for the lack of screen-shots, but I don't have all the anime readily available.
