I have one of those clamp-on types that braces against the brake lever, and also a Crampbuster palm paddle. Neither is all that great; the clamp slowly slips and the paddle still has to have your hand on it, although you don't have to grip it. But I ain't paying for a Kaoko.
I really like my Kaoko.
I find it very easy and convenient to use and sometimes also tighten it just a bit to make my hands a bit less 'eager' on the gas... Kind of difficult to explain, but if its a bit harder to turn the gas handle, you are also less like to rev the enige too much or too abruptly..
It feels like my mpg benefits from it, not sure if it really does
I'm not actually familiar with a Kaoko, but I have had so many crappy old bikes with sticky throttle cables over the years that I will not change a bike that has a smooth, easy pull to one with more drag. If they don't drag when released, that's fine, but they seem fairly expensive for what you get.
I have a Kaoko. Super low profile and out of the way. I considered the Atlas but not particularly happy about something chomping on my bike. I feel like that has a more finite life to it. Maybe I don't know how it works and it doesn't do that, but the teeth lead me to think otherwise.
I have had the atlas for about 2 yrs. Now it works pretty well. Used it on multiple long trips the downside is the little rubber pad dries out over time and needs to be replaced every couple years because it will start to slip slowly, it always locked and never didn't work but just started to slip slowly recently with the vibration of the bars. Luckily they are just stick on floor protectors that you would stick to the bottom of a chair or piece of furniture to keep it from scratching your floors so at least they are ubiquitous and can be had at any hardware store for pennies. All in all its recommendable but if you want simplicity and durability and longevity i would go with the kakao.