Start with http://www.rocketstackrank.com/2015/09/finding-hugo-worthy-short-fiction.html to understand what the site is doing.
Then find http://www.rocketstackrank.com/p/magazines.html#LibraryAccess to discover the various ways to access the magazines.
Then off to http://www.rocketstackrank.com/search/label/Ratings to find the stories.
What i find interesting is that the analysis shows Asimov's stories declining in the award finalists, yet, of the eight stories with a five ranking, four are from Asimov's.
Lightspeed seems agreeably accessible (collections of issues sold as eBooks) however.
Not like i spend much time with fiction these days.