The North American Vexillological Association did a survey of state and provincial flags of the United States and Canada in 2001. It ranked Maryland's the fourth-best, behind New Mexico, Texas and Quebec: http://nava.org/digital-l
But I'll be the first to acknowledge that a lot of state flags look like they were made from a template. There are a whole bunch that just put the state seal on a blue field. There's nothing to really distinguish the flag of Pennsylvania (where I live now) from those of a bunch of other states. I suspect it has a lot to do with the fact that changing a state flag means considerable expense to make new flags for every public building in the state.
"Most of these flags didn't seem to be designed to be aesthetically pleasing, but to carry some other function."
Well you've answered your own question right there. Flags aren't designed to be fine art. They are designed to be distinctive and symbolic.
The US national flag has 13 red and white stripes to commemorate the 13 original colonies, and a star for every US state. The flag of England evokes the St. George's Cross (St. George is the patron saint of England). The German flag has the colors black, red, and gold because those are the national colors of Germany (there are varying explanations as to why).
That some of these flags happen to be aesthetically pleasing to the eye is purely a coincidence.