O/R mapping

hi,
i want to know which o/r mapping tool is the best. I need to get compares on the internet. People who use any o/r mapping tool could help through. If i could find something like Toplink or better but which cost less.
Does anyone have good links for compares or could give some infos, advises for follow tools:
CocoBase Enterprise O/R, v3.1
J-Database Exchange (JDX)
JRelay
ObjectSpark
Relational Object Framework for JavaBeans (ROF)
POET SQL Object Factory
Java Blend
I need more compares for them!!
$Regards