Here are the buffers I have and just a small thought about each one:
1. Meguiars G110v2 - Loud, underpowered, and quite a few vibrations. Demoted to only being used with a DA brush attachment.
2. GG6 ver. 3 - Quieter, powerful, and comfortable. Love this machine. Corrects quite quickly also.
3. Rupes 21 - Quiet with hardly any vibrations. Great machine if you use the right technique(little to no pressure) and products. Corrects very quickly using the right technique. I did notice that vibrations change depending on what pad you're using. With the Rupes pads, hardly any. With Lake Country flat pads, good but it does have more vibration.
4. Makita 9227c - Good buffer but heavy and can get uncomfortable after continuous usage. A good all around buffer though.
5. Bosch lightweight rotary - A basic knock off of the Flex 3403. Same size, almost the same weight but lacks power and can actually bog down quite a big with not much pressure. Well build machine though.
6. Flex 3401 - This buffer is my go to DA/Forced rotational. It corrects super fast and is comfortable. I took the handle off and it was easier to control. Not super loud but not quiet either. Built like a tank. I use the smaller backing plate in able to use my 5.5" pads and it kicks butt. Compared to the Rupes I feel like it corrects faster even using great technique. Not that you don't need to use a good system with the 3401 but you can concentrate more on your goal instead of making sure your doing everything just perfect with the Rupes.
Flex PE14-2 rotary - The best rotary buffer in the world in my opinion. So comfortable and sooooo smooth. This is my go to machine above all listed here.