Logitech G900 Chaos Spectrum Professional Grade Wired/Wireless Gaming Mouse

Pros: I bought this because replacing another G9X (my favorite mouse up until now) was going to be too costly. I was wary of a wireless mouse, but the included cable can be used as a permanent attachment, so I bit the bullet and thought I would try it. If wireless was not up to snuff, I would just plug the cable in and leave it. Boy, was I glad to be wrong, and have an awesome mouse besides.
-No input lag in wired or wireless mode. At all. And I play at high sensitivities within a tiny (about 3.5-4 inches around at the extremes) movement area on all of the games I play.
-Lightweight
-Side button swapping to change it to left-handed (or just to add two more buttons on the opposite side of your thumb)
-Battery life
-Build quality is top-notch. The thumb buttons are not "mushy" like my G9X's
-"Surface tuning" in the Logitech software
-I don't use DPI switching on the fly, so being able to swap use the DPI buttons as a generic mouse button for extra functions was awesome
-Free-scrolling on the wheel has its switch moved from an inconvenient spot (the bottom of the G9X) to the best logical spot (right behind the wheel)

Cons: I will have to nitpick here to come up with cons.
-If you are a palm gripper, the side buttons may be just a tiny bit too far back for your liking. But we are talking millimeters here.
-This is really digging, but it would be neat if I were able to pick a handful of colors for the lighting and have those cycle. As-is, you can have the full spectrum cycle, one color (with "breathing" option), or lights off.

Overall Review: It's at a pretty premium price point, but I don't regret a penny of my purchase. The G9X was legendary, but this is a worthy successor.

Pros: Really good response time.
Very light mouse.

Cons: If automatic profile switching is on mouse buttons ALWAYS release upon the profile switching which has a moderate impact on productivity and is kind of a kick in the pants every time it happens. (example: http://i.imgur.com/JJpCSTq.gifv)

It's like getting a new sports car and finding out every time you change the radio station your car goes into neutral.

Hopefully this will get fixed in a firmware/software update.

Overall Review: If you are having trouble gripping the soft-touch plastic on the mouse, applying a strip of glossy scotch tape to either side will help.