I look like Robin...
In the warmer times, I like a tan-colored nylon fishing shirt... doesn't really matter what brand... current one might be Columbia or PFG? I've also used CampMor and many others over the years. The main point is that I like a gusseted shoulder joint, a ventilated flap/yoke on the back, a normal collar (and you'd be amazed at how convoluted a collar with velcro fasteners can get), two-button sleeves so you can close it tighter, a middle button under the forearm to make rolling it up easier, and good chest pockets. I prefer buttons. I like when there's a little zippered pocket behind the left one. I also like when there's a little loop for tying off my compass or GPS on that left pocket as well. Oh, and long tails, preferably down about even with the pants crotch.
In cooler weather, I have a red plaid light fleece shirt. By itself, no wind, it's good into the mid 60s if I'm moving around outdoors. With a windbreaker or rain jacket over top, it's good into the 50s. I have another thicker one, blue cotton shell, lined with fleece, for 30s-40s, and another blue one with a thick pile lining that, with the wind breaker, will get me into the 20s-30s.
The red fleece one is good in the Adirondacks in late April and early October.