best loop file format

What is the best format for loop files? I see the company has the loops I want in WAV, AIFF, REX2, and STYLUS RMX file formats. Does it matter which I buy? Which is best, most flexible, easiest to use, for Cubase users? Thanks!

For me, REX is the king of loops. The lack of any time stretching keeps them sounding the most pure. Cubase just brings the files in with the hitpoints assigned and audio slices made. From there, it’s a cinch to mute or pitch or stretch individual slices to do what you want.