The first real "gaming" mouse that I bought was the Logitech G400S. I used it for about a year. Not the biggest fan of the shape but my biggest gripe was the scroll wheel. It never felt comfortable to use because it's hard and sharp for both scrolling and clicking.
Then, I replaced it with a Cooler Master Storm Recon. Used that one for about 6 years or so. It is a good mouse but it's been seeing normal wear and tear and have gotten somewhat uncomfortable. I still love the mouse, especially when you consider the price (it was relatively inexpensive). Too bad CM stopped making them, or at least that's what I figured because it was somewhat impossible to find anymore.
Finally, last May or so, I decided to change to the Steelseries Rival 310 and been using that since then. The shape is fantastic but I'm not the biggest fan of the rubbery grips on the sides. They feel kinda slippery, but I have gotten used to them. Considering the price, I hope this mouse will last at least as long the the CM Storm Recon.