(I'm ReSharper Product Manager, take with care)
For me it is not specific features that make most sense here, you can make up any numbers on comparison charts by categorizing things, e.g. you can count formatting actions as refactorings. Also some missing features here and there can be complimented with other plugins - being them within tool's ecosystem or VS ecosystem.
What I really find important for any tool of this kind is deep and accurate code understanding. Some tools, unfortunately, are not that accurate. Every product has bugs and issues, of course, but being not able to accurately resolve symbols is show-stopper for me. May be not for other people, who value fast typing over accurate analysis and refactoring. Other tools in this area cannot even parse C# code sometimes, not to say about resolving generic overloaded methods with lambdas and correctly supporting LINQ patterns.
As for complete, direct and independent feature list comparison, I don't think there is one. I believe every product has comparison chart with Visual Studio (ReSharper has), so you can combine them, and then clarify specific points with the community and users of corresponding products.