Well, seeing as it's normally hot where I live, my most common wear is shorts and a T-shirt. The T-shirts usually have funny phrases or slogans on them (I'm wearing one right now which says "I Don't Do Mornings") and the shorts just need to be the right length (around the knee area).
I don't really consider these "comfort clothes"... To be honest, the most comfortable thing I've ever worn is a black cotton skirt. But a guy wearing a skirt down where I live is just asking for trouble. Sad, but true.
In the winter, I still wear T-shirts most of the time (never long sleeves - I hate long sleeved shirts, T or otherwise) but usually with a black jacket. Not any material I know the name of, but kind of silky-smooth, and doesn't heat you up extensively. Considering it's never snow weather here, and most places blast the heating during winter, a thin jacket is perfect, and then if necessary I can take it off and just sit there in a T-shirt. For most of winter, I wear black dress pants, which I prefer over shorts. But I don't wear them as often as I'd like, as it is usually too hot for most of the year.
Most of my clothes are black, harking back to my pseudo-gothic days. When it's raining, I have this cute little black umbrella, which I love and bought for $2. Total win.
I wear glasses all the time, except when in bed or in the shower. I wear a silver-plated steel watch except when in the shower. Sometimes I wear a pentagram necklace, harking back to my Pagan days (I'm an atheist now though, but I still like pentagrams).
I don't own any sweatpants or jeans. I think sweats make me look silly, and jeans don't feel very comfortable to me.
So really, all my wardrobe is comfort wear, I suppose - not specifically because it feels comfortable, but because I feel more confident when wearing evidence of my own unique style.
But seriously, the world needs to get less judgemental and violent, so I can wear skirts without fear. Most comfortable thing I've ever worn. It let's air in on hot days, but looks better than shorts. It can keep you warm on cold days to some extent, but you don't overheat. I don't see why it should only be girls who get to wear them.
But hey, I'm a trendsetter.