Interesting comments above. I've had this discussion before, and most people feel strongly one way or the other. In most facilities, I've been allowing the electrician decide based on their preference for many years.

The Air Force required compression fittings because they considered them superior in longevity & EMI protection.

The only standards based reason for one fitting over the other that I'm aware of can be found in IEEE Standard 1100 "IEEE Recommended Practice for Powering and Grounding Electronic Equipment". This standard is concerned with the performance of electronic equipment and how the power system plays a part in that. Paragraph 8.4.8.2 (on EMT) "Sections of this conduit are typically joined by means of setscrew or compression-type connectors, which do not provide the same magnitude of grounding integrity as threaded conections. Accordingly, the shielding and grounding effectiveness is reduced. Recommended practice is to join sections of electrical metallic tubing with compression-type couplings. Set-screw-type couplings should be avoided. Connections to enclosures should be made up tight using compression-type connectors." In this instance, I believe the text is referring to high-frequency grounding paths and EMI concerns. In paragraph 8.4.8.5, "Conduit Fittings", there are several methods concerning bonding-type bushings, locknuts, etc. that are above and beyond the code minimum and above standard practice for most electricians. It all refers to high frequency EMI.