So, first off lets talk about the bank. This is an item that you should not skimp too much on. You need to be able to trust is rain or shine; having a failure halfway through an overnight cook might not be a good thing. I did a lot of research and went through one return before I got what I wanted.
If you live anywhere that has rain (most people do) then be sure the unit is 100% waterproof. It amazed me how many of these were not. Crazy to be halfway through a cook, have a downpour, and lose your unit until it dries out. I first bought the Soraken but returned it after the display went blank from sitting in the sun for about an hour. I guess the cheap LCD couldn't handle the heat. By the way; it is not waterproof. That was the second reason I returned it...I realized my mistake.
I now have the Inkbird IRF-4s and am quite satisfied with it. Works well, has great range, and is waterproof. 2 Probe unit is $60 and 4 probe is $75 on Amazon. Fully waterproof and the battery life is amazing. I've done at least 4 cooks since I got it; probably 20-24 hours of use and the battery levels are still over 50% from the first charge. Customer service is also great; my "oven" probe (the blunt tip one) failed after the first 3 uses (another good reason to have some extras) and they responded within 24 hours promptly shipping me a new one.