I too have several UA tee shirts, both long and short sleeved, and both black and white colored. I always (almost always) wear a long sleeved one any day I ride summer or winter. The need for some sun protection is very great here where I live and ride. The long sleeves combined with sunscreen underneath give me good protection from the sun. I also wear a mesh jacket anytime I ride, and in the heat of summer, my wife and I wear neck cooling wraps as well as a cool vest over the longsleeved shirts and under the mesh jacket. It's the only way you can really survive without roasting inside and out here in the hot dry summers.
I also own some heat gear long undies and some cold gear of the same. I have found all these items from UA to be of very good quality and very useful to us as we ride any time of year. They are thin and comfortable underneath riding pants or jeans (I'm way bulky enough as it is, and don't need any additional!). I wear the UA stuff as an undershirt year round, and find it to be comfortable and very tolerable. What I like most is that they do not capture and hold moisture and become clammy and wrinkled, especially in the butt area of my pants. They work extremely well underneath the cooling vest in hot weather. And they are much more comfortable in every way as compared to cotton. I like UA stuff very much. There are other brands that may work as well and may also be cheaper in price. Whether they will last as long as my UA stuff has, I don't know. I've been wearing some of mine for almost eight years. Good stuff!
