After a lot of reading and research, I went with the Pieps DSP. Its not as flashy as the Ortovox or the Mammut, but its better as a beacon. The range and reaction time is superior, the new case that comes with them this year is comfy and out of the way (the old case sucked), and its simple to operate.
The truth of the matter is that all of the highend beacons are good, but the qualities you NEED in a beacon are slightly superior in a Pieps.
The Ortovox is finicky and can get lost if movements are too fast, the mammut isn't quite as intuitive, and I haven't had my hands on a new style beartracker yet. The old style beartracker doesn't compare with the accuracy of the new beacons, but is a solid beacon.
Whatever you choose, just get good with it, I've seen guys with old analog beacons school people with their fancy new beacons and its all because of practice.
I don't sell beacons so I have nothing to gain from your choice, I just spend a lot of time skiing places that can kill me so I put a lot of weight on my beacon selection.
That said, all of my friends and I wear a DSP.