Signature ability index?

Does anybody know of any public website, spreadsheet, forum, or tool, where there is an index of 4* and 5* sig ability levels? I'm constantly asking my alliance and the forums about what certain characters are like at a certain signature level. IF there was one out there it would be immensely useful to all summoners seeking to invest their stones in the right places. For example, this past two weeks I duped both my 4* Guillotine and my 4* Doctor Strange and haven't yet been able to decide the best use of my mystic signature stones... Or if I should wait for another mystic champ to use them on.

Any thoughts, anyone?