No headphones because humidity. Perspiration everywhere. Earmuffs become a sticky mess, in turn making my ears uncomfortable. Ass sticks to chair (ok... nothing to do with headphones). Air-conditioning helps, but I don't like the cold, and find myself wearing a jersey on temperate days already, so you won't find me in the northern hemisphere anytime soon.
That said, I prefer headphones when playing DT and fast maps. I hammer my keyboard harder as things get faster, which drowns out the music and hitsounds with just speakers.
So basically, I use headphones when their benefit is needed, but most of the time I play casually and just use my speakers.
