For gaming the AKG K7XX are really good headphones due to their wide presentation and mid-range presence. They are also easier to drive than both the 58X and 6XX, which is a plus. Really the bass is respectable on them, but possibly not as good as the 6XX (I cannot comment on the 58X).
Frankly all 3 of those options are great headphones, but I'd imagine you'd want to have a decent headphone amplifier if you used the 6XX, which increases your budget.
Keep in mind gaming mixes vary in quality drastically, too, so sometimes it doesn't matter how good your headphones are, the sounds are still going to be mushy and congested.