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.