Hi Yamahauler,
Just look at some filters up close and you'll notice a few differences. Just like with corrective spectacles, there a lot of different materials and coatings. Don't be neurotic about specifications, just have a pragmatic look yourself.
Image quality: Put some filters on a sheet of white printing paper. Rule out any filter that that shows a colour cast to the paper beside it (low quality glass or plastic "optical resin" with a brownish cast). Then look at the paper texture and throw out the ones that make it look less visible (that eliminates the cheap plastic ones). Theoretically, you could test it in more detail, but no one will see the difference anyway with everyday photography (remember to remove filters for special things like portraits and macro).
Behaviour: try the lens in difficult situations to check out the reflections: shoot in bright (sun) light, sun falling in from the side. Or try a reflective object (chrome piece of a car maybe) to see what happens. The less flare, the better!
Usability: distract the sales person and secretly put some dust on the filters (or shake your head in case of dandruff). Now see which filter (coating) allows you to blow it off easily. Then do the same with wiping. If you want to take the risk, do a fingerprint test
Next, see if it rattles in the fitting. For larger diameters you might want to choose a brass fitting as brass has less thermal expansion so your filter will not get stuck on the lens.
The trade off is that the better the filter is coated, the better the behaviour and the more problematic the cleaning! Clean, pure, flat glass is easy to clean, but reflects too much light! Coatings make the surface a little rough and a pain to clean. It's your own call where on the balance you would like to be. Do you throw your camera around and take a million pictures or do you treat your camera like a baby only to remove the lens cap for an instant masterpiece?
I'm in the first category and use a lens hood to both help fight reflections and minimize the change of getting fingerprints on the filter. And to absorb to blow if all that stuff slips through my hands