The Sun implementation is easily the most common version on Windows.
It has been years since I saw a JVM speed shootout documented. I get the impression that alternate JVMs have been optimized for different environments - for example the Dalvik VM used in Android phones.
"Better", as I've already remarked once this morning, is a relative term. So Bill and I concur. IBM's jikes JVM used to be considered hot stuff, but I don't actually know these days. I try not to code so "close to the wire" that it makes that much difference. Usually a better algorithm makes all the difference.
One thing I did notice on the Android coding guidelines were that a number of their low-level optimization recommendations shouldn't be applicable when compiling with a modern-day Java compiler. In other words, the compiler would normally have taken care of the issue before the JVM ever had to worry about it. Which worries me. Do they know something I don't, or do they just "know" something?
An IDE is no substitute for an Intelligent Developer.