powerscol, this question has been asked many times and in many different forums. Yes the choices, along with the range of prices, is mind boggling. Basic considerations are budget, how loud is the noise you're trying to suppress and whether you want a self contained unit (wireless) or wired. My worst scenario was cutting grass either with the tractor or my ZTR because you have the engine at full throttle plus the sound of the blades whirring. I don't think you'll find anything that will completely eliminate all the noise, but you don't really want to. If something goes haywire you want to be able to hear that. I've tried many different setups over the years starting with the older Worktunes, which is an AM/FM headset (newer ones can also be plugged into a MP3 player or phone. They are reasonably priced but radio reception wasn't very good in the rural area where I lived. I've also have a couple of different noise cancelling headphones, both wired and bluetooth enabled. Headphones are the most comfortable way to go, but in my opinion, don't give the best results. Here is my setup of choice, especially if you really enjoy listening to your music. I have my music on my smartphone, so I use a mid-priced bluetooth, noise cancelling earbuds. They came with different size cushions to fit your ear. Being in your ear, they give the best sound but not the best for eliminating outside noise. That's why I use an inexpensive pair of Peltor ear protecting headphones over the earbuds.
There's a lot of choices out there. I would only suggest not buying anything really inexpensive, but on the other hand, there's no need to spend hundreds like on some of the high end noise cancelling headphones like Bose. To answer your question about weather rating, I don't think any of these devices are made for storage or use in the rain. But if you want to just store them outside on the machine you could simply use a food storage container or even a zip lock bag.