I really love the Logitech G502. It has those buttons on the side as well as being programmable do doing whatever you want. The scroll wheel is also amazing, because it has a lock to turn it from normal scrolling to a wheel you can spin to quickly scroll through stuff. The best part is the weight though, it comes with weights you can put into the mouse to change how it feels and where it's heaviest. It's great! No middle button though, but you can press the mousewheel, and that's programmable. It does have a grip on the side for whatever reason, though. There's also a wireless version!
