you can compare the core clock & memory clock speeds between any available models
and you can look at the cooling solution offered to see which shroud+fans appear to be the best cooling option.
many product specs will even offer information regarding what sized fans and what RPMs they can run at.
reading customer reviews of products and tech review articles for certain versions will also offer some information as to which may offer the better performance and how hot they may run.
the Nvidia FE versions should be quite a bit cheaper than any 3rd party versions at MSRP.