I might be missing something, but I can't see how any third-party "resource" can help you with this. Surely, it's up to you to decide which alternatives you want to test, and then to go ahead and try each of them in turn, and monitor the results. What additional help would you expect a third-party tool to provide?
Also, you have to define what you mean by "better". In other words, what are your critieria for success? Are you looking for the title that performs best in SEO terms? If so, that will be hard to measure, given the large number of variables involved (many of which are outside your control). Or are you looking for the titles that will be most helpful to your readers - which would be even harder to measure, of course?