The 215D is powered, and has a significantly higher max SPL than the 215XL. The 215XL is passive, and will require a separate amp to operate.
The 115W (apart from the wireless) goes 10Hz lower (45Hz vs the 55Hz for the other 2,) and can mix 2 mono sources (so it can essentially take a stereo input and crunch it to mono,) whereas the other speakers can only take a mono input.
One thing to consider is how you're going to be setting them up. They're all pole-mountable, but they all have different mass, 31lbs for the 215XL (lighter than the others because no internal amplifier and the heavy transformers associated with that,) vs 38lbs for the 115W, vs 45lbs for the 215D. If you've already got amps the XL is a no-brainer. If not, and they're to be portable (and you'll be by yourself to set and strike, you might want to pay a premium and get the 115W and save your back 7lbs per speaker.