that would depend on your grip style and if you find it comfortable to use side buttons arranged in a grid.
personally my choice mouse is the deathadder with its two large buttons since it fits my grip style and i can manage the side buttons easy as it only has two.
the logitech proteus has more buttons on the side and i found it fairly easy to use that layout surprisingly although the mouse was a bit too narrow for my liking so i did not keep it and revert back to a deathadder. otherwise i found using so many buttons to be very easy due to the unique locations associated with the buttons.
i have tried out a g600 in the past which has a similar button layout to the venus and i found it much too hard to navigate both the mouse...