If those are your two choices, get the M1.
That is my recommendation and it is because there are many settings.
People are individual in their responses. I love Schumann, but other people love Omni.
I loved having the TMS settings to experiment with because I was copying a lot of TMS studies and this is a much milder version of TMS, but it is useful to have multiple settings.
With the M1, there are settings that the self-hackers asked specifically for and there was a reason for all of them.
For instance, the M-1 has a gamma setting and MIT used pulsed gamma in their Alzheimer’s study.
The M-1 has alpha, beta, gamma, theta and those are used for things like focus for tests or sleep or relaxation.
The M-1 has settings if you ever break a bone or are in pain and when I originally got it, I had chronic pain of my ankle and that has gone away. Studies of PEMF with pain say that it is similar to a mild opiate and if you ever need surgery or get injured, the M-1 will pay for itself.
I bought the C-5 partly because I will be using it to see about preserving cartilage in my knees and hips.
I paused because I got sensitive to it and that happened a few times to me and I take a break for a while and go back.
But that sensitivity is different on different settings and different powers. I personally do best when it is low power and I can’t hear it, but I know other people feel comforted by the sound eventually. I am sound sensitive so being able to switch settings to a quieter setting helps me often.
The M-1 is more mobile and it is light weight.
When I was injured, that was the most important part.
With the C-5, I mostly only use it for a few hours at a time when I use it so being plugged in isn’t a bad thing for me.