Which of these mice should I get?

I have the logitech g303 and I love the light weight and it's easy to click. I'm getting a new mouse and want something that is also very easy to click because of developing arthritis. I can't find any specs online of 'force required to press mouse buttons' so I have to ask for anecdotes..
The choices I have are the G305, g603, g600, or mx518. Which of these should I get that is the easiest to click and lightweight. Thanks