I use this wireless USB Logitech mouse and like it just fine — it uses a wireless USB receiver instead of Bluetooth, which I hate, and it's small enough to throw in my bag if I need to use it with my laptop. I don't feel super strongly about it, but I like it and you can't beat the price.

I've been using the same Logitech MX300 for about twelve years.

Try Logitech MX Master or the newer version MX Master 2S
Feels great in your hands, super fast and crazy accurate.
Setup your custom buttons and you will never go back using a other mouse, believe me.
Best mouse out there.

Best mouse I've ever used? The Amiga's legendary "pregnant badger" model in the 90s:

I use Logitech B170 Wireless Mouse

I use the Logitech B100, the better I've use ever. I work with this mouse all day with no wrist or shoulder pain. But your ergonomic site (chair, table) has to be well set up.

I use a Razer Abyssus 2014 mouse. Light weight and cheap.
They call it a gaming mouse but who cares it is great for work also.

I like the current Apple mouse ("Magic Mouse"), mainly because the surface works like a track pad, allowing zooming and multidirectional scrolling with no moving parts. It also has one- and two-finger swipe gestures for switching between pages or screens, which I use. I might look like it has only one button (the entire surface), but it has both left and right button function. And I like that it's wireless.