When should I choose an x64 version of a vendor's application?

"Applications compiled specifically for X64 should have better performance since they would not require an emulation layer.

Software vendors that provide both 32 and 64 bit editions of their products, probably do so with good reason. For example, they could be tweaking an algorithm to use different size floating point variables or memory addressing that yields greater performance.

Some vendors might also provide a ""change log"" that outlines the differences between the two versions, which could be reviewed.

I personally always choose to install the x64 version if available."

In my opinion, if the vendor provides both, you should always download the 64-bit version, if for no other reason than that it doesn't make sense not to. There is no downside to using a 64-bit executable, and at the same time there are multiple advantages to it (mainly speed), so why not?