I would recommend the Pieps or the BCA over the SOS and the Ortovox.
BCA is very easy to use, digital beacon, 2 antennae.
Pieps is very easy to use, digital beacon, 3 antennae.
SOS is analog and requires a lot more practice to become proficient.
Ortovox has multiple models, which we carry, but we are not as impressed with the ortovox as we are the other beacons.