In a lot of ways, this isn’t an apples to apples comparison.
Essentially, ColdFusion is a RAD Environment for Java. CFML code compiles down to Java Byte code.
Capability wise, I would say that ColdFusion does more out of the box, but it is also a 9th? generation product, or 3rd if you count them going from the C runtime to Java. It offers integration with Flash and Flex, and event gateways, it has a better error handling and debugging framework (in my opinion), and a few other items that you don’t get with Rails. Rails also offers some things that you don’t get with CF, so that would really depend on what is important to you. ( This section of the email would have been a lot longer, but I am pressed on time right this sec.)
Performance and Reliability depends more on you than the language/framework you are using for the sake of this comparison. Both are reasonably stable products that run medium scale things today. You could write equally crappy apps with both, or excellent apps with either. I wouldn’t recommend CF for really big multiple server projects, as evidenced by MySpace’s migration to Blue Dragon, the CFML runtime that runs on top of .NET.
So I guess the moral of the story on there criteria is that, it all depends, at least in my opinion.