Use 2.1 stereo headphones but if possible use virtual surround sound or Dolby 5.1 through ur pc into the headphones , this will give you far better awareness.
Headphones designed for audio 2.1 will always be far superior quality speakers to the 'gaming' headsets which cram 5 or 7 tiny speakers into each ear.
I use Beyerdynamic headphones (DT 990 premium) after trying many brands i found these to be most comfortable and nicest sound. Open headphones like these will not 'clamp' your head, the closed headphones are much more pressured and tight feeling.
I would recommend seperate headphones and mic, something from Beyerdyamic or maybe Seinhesier. get them off Amazon as you can return anytime and get a good warranty.
The soundcard also makes a massive impact on the quality and situational awareness. I spent about £70 on a Creative Z soundcard, this has a surround sound virtual mode which emulates 7.1 speakers through a 2.1 headset. There are lots of good soundcards, if you are using the built in motherboard soundcard you will unlikely to have virtual surround sound and will be stuck with 2.1 audio which isnt very situational. There is a cheaper option realtek DX soundcard for about £25 that has a decent virtual mode also. Some of the more pricey headphones will come in different ohms, so you need to make sure soundcard has correct pre-amp to drive the ohm level, or buy a seperate headphone amp which the soundcard plugs into.
When I was researching I would read Mad Envys thread about headphones , very famous online headphone guy with nearly every pair tested
http://www.head-fi.org/t/534479/mad...-guide-3-18-2016-mrspeakers-ether-c-1-1-added
ps., the mic i use is called 'modmic.' these mics are great and can clip onto any set of headphones or surface. It comes with a couple of magnets so u can just pull it off when not using it.
http://www.modmic.com/
much luv