There is no rating service that I know of, but there are lots of deciding factors you can use:

Is it still maintained? Good indicator is if there was a new version in the last year (don't depend on it, some old modules are so "finished" that there is no need for a new version)

Is there talk about it? Search perlmonks if it is mentioned in any threads. Often the thread tells you of alternatives and which is the best mod to use in most cases

Which one has the features and interface you want? Often modules are all of high quality, just for slighty different needs or tastes

If that still doesn't decide it, look at the source package. Does it use warnings and strict? Has it lots of tests? The number of tests and whether they fail on lots of platforms can also be looked up at http://static.cpantesters.org/