You definitely want a digital beacon and not an analog beacon. The analogs work, but they take a lot more practice.
The Tracker DTS has two antennae and is very easy to use. Once in a while, because it only has two antennae, you will come across a "spike/dead" reading that occurs when you move between flux lines, this can sometimes be a little confusing unless you know to just move right through the "spike/dead" reading. This being said, it is still very easy to use and the most popular beacon out there.
The Pieps has three antennae and therefore the spikes are eliminated and it also (IMO) makes multiple burials easier. But multiple burials don't happen near as often as single burials, and if people would only have one person on the slope at a time (and out of the runout zone), you wouldn't need multiple burial features. The pieps is an excellent beacon, but it has a tiny bit slower processor than the tracker, so it may take a split longer to process the signals coming in.
The Mammut Pulse is a SWEET beacon. It has three antennae and also has analog capability to give it some additional range. It doesn't have the spike readings like the tracker, it is easy on multiple burials, and it also has a feature that will transmit if you still have "a pulse" to other pulse beacons. However, the Pulse has a menu on it and you could even put the menu into chinese if you wanted, so it is a little more complex than the other beacons and will take a little more practice.
Hope all this helps. Everything being said, there is no substitue for practice. If you practice enough and know every feature of your beacon, I don't really think it matters in the end which beacon you have. Everything you need will be on top of your shoulders.