I changed from a Razer Mamba to a G502 and couldn’t be happier.
It has the high quality feel of Logitech product. I should of known not to move away from Logitech in the first place. It was an expensive lesson.
All the buttons are it the correct positions for easy use. The wheel feels nice. I've got nothing bad to say about it so far after about a year of use.
I have used the M60 and I was considering it when I purchased the G502. Luckily my friend bought one first and warned me about the thumb buttons. They are placed in an awkward position which was the only complaint I had when I went over to try it out.
Corsair are a bit of an unknown to me as well so after the bad Razer experience I decided to stick to Logitech as everyone I know...