I think the 1 - 5 stars approach works well as with the GUK system. Despite what everyone thinks or supposes about it a few caches in each area got a consistently high rating marking them out as exceptional in the view of everyone who did them.
As we only used it to identify the top % in the areas we were visiting it made it usefull to draw up a short list.
We never used it to filter out poorly rated caches it was only for that top set.
To us the current set up on GC does not help you filter for what you like.
Caches need to separated into categories. Categories the visitors and owner can vote on (to prevent lying)
Lenght of walk to cache. Height gain to cache. Type of terrain (split as per handicaching)
Difficulty of hide of cache. 1 easy to 5 high degree of camoflage may require multiple visits / PAF
Difficulty of puzzle. 1 sudoku - 5 phd in subject required (most are solved at meets strangely!)
and things like night cache, scenic view, good walk, part of larger series (alchemy style etc), cache and dash etc
"If you can't be a good example, then you'll just have to serve as a horrible warning."