Which gaming headset should I buy?

Logitech g35, but the best are the Astros a40 with mixamp, mlg official headset

I too made the mistake of buying the Razer Carcharias... I can't speak for the Vulcan or the Psyko but I can say that the G35 has some cool features. I owned the G930, the wireless version for about a day. The wireless doesn't work too grand when you have a wireless keyboard and mouse also, they interfere with one another. The G-keys were nice, they were a little heavy on the head and the sound quality was just so-so. The virtual 7.1 surround was really wonky. Even after adjusting all the settings, noises directly in front were muffled but I could hear someone shooting on the other side of the map like they were right next to me. Tritton makes some good stuff, they always have. If you want sound quality then get the Sennheiser. I can't attest to their gaming performance but Sennheiser knows how to make a pair of headphones with high quality sound. Just as a suggestion from someone who just spent a month trying to find a good headset myself, I would suggest you take a look at Steelseries as well. I settled on the Siberia V2 and even without the external sound card you can purchase, they sound great. And they are incredibly light weight.