Two antenna beacons will work. A lot of lives have been saved with them. The three antenna versions are much better from a search stand point. Dead spots are eliminated, less variations due to burial angle, that sort of thing.
For the money, the Pieps DSP is probably the best beacons out there. Good balance between features and functionality. This is the base model. They do have one that has crazy other features, like an inclinometer, barometer, and shit you don't really need on a beacon. The range is search mode is far better than just about any beacon out there. You can pick up a single from 60+ meters out. The BCA2 and most others are lucky to hit form 40 meters. That is a huge difference. There is one other beacon out there that has that sort of range, I think it's the Ortovox 3+, but not 100% sure. The DSP also has the ability to search for an alternate frequency transmit only beacon they make for dogs. Since I ride with my pooch all the time, it's a great feature.
The bottom line is that, all of the digital beacons on the market are effective. You need to know how to use them, which means practice, practice, practice. Things to look for is that the beacon is simple for you to use. If it's complicated, imagine that in a life or death scenario. Not good.
As everyone mentioned, the beacon is no good unless everyone else in your group has one. On top of that they will also need to have an avalanche shovel and probe. If you don't have all three of those items, then you might as well not have them at all, and you you have no business riding in the backcountry as you obviously have no idea what you are doing. Education is also key.
All that gear is great, but it doesn't protect you. Getting buried in an avalanche generally means broken bones and life threatening injuries. Keep that in mind. Paralysis, long hospital stays, expensive medical bills are common, and of course there is also that death thing. You carry the stuff as a last ditch effort, but if you need it, you've fucked up big time. Better to have a gun and not need it...
It is a lot of fun, don't get me wrong. It's all I do. I've also seen several bodies being recovered after a person was caught in an avalanche. Most of them had all the gear listed above, and they are still dead. One of them was from two seasons ago. Chatted with the guy about his set up in the parking lot before him and his two friends went out. He didn't come back. That is how quickly shit goes south on you.
So beacon, shovel, probe, and training. All of that should be on the list. If one is missing, you are not prepared at all.