My Droid 4 doesn't give me the option to choose media sync or mass storage.
Yes, USB debugging mode is enabled.
Yes, I've unmounted and remounted my SD card.
Yes, I've rebooted my phone.
Yes, I've attempted this on 4 computers:
1 with Linux Mint 12, 1 with Kubuntu 12.04, 1 with Windows 7, and 1 with Windows XP.