My personal experience with both is that decompilers work great for easy code. I still have both Java and C# projects that I wish I decompiled even to worst possible, but almost compilable code. Instead getting just decompiler errors or code where all variables got the same letter/name and of course different types...

I think I've tried all available free tools and some paid in Java case. Finally I just deducted logic and reverse engineered the most important path.