We typically recommend 2 ANT USB sticks for development, as you may use each stick to simulate each side of your link. As you have a working ANT+ device you may only require 1 USB stick.
Any ANT USB Stick such as the USB-m, USB2, UIF + Module, etc may be used. The USB-m is the latest and most compact model, and it has some newer features such as "high duty search" to minimize search latency.