The best you can afford. Make sure it is set up to the new frequency standards (don't buy an older, used one!). You probably should go to a store and test drive a few.
By the way, most avalanche victims die if they are caught. The transceiver is more often used to find the body. So invest in a good avalanche course to not get into trouble in the first place. You'll also find out about the transceivers and how to use one.