Recs.
Updated
The Zowie FK1+ is a large, ambidextrous mouse that is great for competitive gaming, particularly FPS. With a notably safe shape, it can be used with many different grip styles, either by left or right handers.
Specs
Pros
Pro Good mouse sensor, regardless of whether it's an older FK model or a newer one.
Whether you have the FK1+ with the older 3310 sensor, or the newer FK1+-B Divina version, you'll not have any issue hitting your shots. Zowie's sensor implementations are definitely some of the better ones.
Pro Very flexible cable, albeit not as good as modern paracord-like cables.
The cable is above average in flexibility, and generally quite good at not causing issues mid-game, especially if used with a mouse bungee. But don't think that it'll beat paracorded mice, or similar types of cords.
Pro Mouse wheel is suited to FPS gaming, with very clear steps.
The mouse wheel has fewer steps (16), but because of that the steps are larger and clearer, so it's less likely to cause issues in the midst of a firefight. Note that this can be harder to use in desktop scenarios, as it is slower than normal mouse wheels.
Pro Ambidextrous, with buttons on both sides, allowing for both left and right handed use.
The mouse has an ambidextrous shape, allowing for use by both right and left handed gamers. Ambidextrous shapes are also very good for fingertip and claw grip, so if you use those grip styles, and have a large hand, you're very likely going to find this mouse worthwhile.