If you leave your U2F key in your laptop or PC, I find it to be much more convenient than mobile 2FA. Just one tap and you're in... versus pulling out your phone, unlocking, and typing in the code.
Btw, all U2F services allow you to fall back to phone 2FA if you're on an unsupported device.
Btw, all U2F services allow you to fall back to phone 2FA if you're on an unsupported device.