I like to wear solid color t-shirts when not at work (OK, at work a lot too). My usual choice for materials has been cotton, especially when you can get high-quality shirts at Target for under $10. They look nice, feel nice, and last many moons. The only problem I had with them is that they do not breathe well or handle moisture well. Since I live in GA, that tends to be a big problem for me.
Synthetic or synthetic blend shirts have been around for a long while, and I own a LOT of them. The problem I have found with most of them is that it looks like I just hopped off my mountain bike when wearing most of the t-shirts. They are usually relatively shiny, with loose weaves and maybe a zipper or two. I am no fashion model, but I try not to look like I am training for a traithlon at all times. They also just do not feel as good as a cotton shirt.
Thankfully, REI has some (new?) shirts that help solve my problems. The Sahara Tech Tee is a short sleeve shirt made of 100% polyester. Not just normal polyester though. It is brushed polyester, so it looks and feels like cotton, for the most part. Not quite all the way there, but they are a lot better than your average polyester shirt.
I have been wearing a few of them lately, and have been pleasantly surprised with how nice they are. They fit well, wick well, and don’t feel like a woven garbage bag. REI had them on sale for $15 last week, so I now have 10 of these bad boys in my wardrobe (mostly black :D)). Well, maybe in 6 months, since REI’s store pickup likes to be nice and slow.