If you're getting headphones solely for gaming, the M50x's have a pretty narrow soundstage, which doesn't really help with positional audio queues like footsteps, although it is sometimes blown out of proportion when people give advice for headphones.
I wouldn't get the HD598's at full price, they go on sale every once in a while (I know they go on sale for sure during the winter). AFAIK Sennheiser's G4me headsets are rebrands of some of their other headphones, and while pairing up any headphone with a clip on mic is sometimes even cheaper than getting a headset, some lavaliers (clip on mics) have trouble picking up people's voices and background noise, but a mic on the corner of your mouth generally has less issues (cue ModMic plug, although it isn't really cheap). HD280's have a nice tight fit, which help isolate noise, although some people do complain about the tight fit, which might be uncomfortable if you have glasses, or over extended periods of use. I do believe you can bend them to help ease the tight fit into something more comfortable.
As far as closed headphones go, there's the AKG K550/K553/K545 (Hey, I own these!), although a bit lacking in bass, it's soundstage is pretty darn good for a closed-back. Audio Technica's got some closed headphones like the A500x, A700x, and the A900x's. The A900x's were pretty good for me, although some people don't really like the strange "wingflaps", and how they fit on people's heads.
Good thing to note is that if you get a pair of headphones that requires an AMP, like the HD598's, you might need to buy an amp, or amp+dac combo if you're not satisfied with them just plugged into your motherboard, which could cost you quite a bit.
You could try to find the BEST GAMING HEADPHONE EVER, however, a lot of people are content with their Apple Earpods, and still pound without an expensive audio setup.