>> Wow, the ex officio shirts look really nice. They have ones that are 20% poly 80% nylon and ones that are 50% poly and 50% nylon. Not sure which would be better. I'm assuming the 50% poly shirts will have higher breathability but will sacrifice a little bit of durability
I have both. I like the 20/80 because of the fit and feel. I haven't paid attention to which is cooler. I can also wear them to business meetings if the dress is busines casual. Multi-purpose!!
>> do you recommend the Ex Officio shirts over the Rail Rider shirts?
That is a difficult question.
If it is hot, and lots of water is available, then I wear a Rail Riders Eco Speed T shirt. Loose knit with side panels. But it is rare for me to get a sun burn. I also have many polyester T shirts made by REI, Nike, Adidas, Columbia, and Patagonia Capilene 1. I use them all, but like the Rail Riders best. I have pretty much thrown away all my old cotton T's and wear these for every day wear also.
If it is hot, over 80F and into the 100s and not a lot of water available, I wear a RR Adventure shirt to help reduce evaporation. I keep the sleeves rolled down, even in the heat. I also wear a bandana, ocassionaly soaking it in a little water. I don't need any pockets, except the little pocket for my digital camera. So it is the lightest of my long sleeve shirts.
If temps are going to be below 80F I wear a BPL Merino Hoody.
On day hikes I wear one of several shirts, but all similar construction: Rail Riders, Ex Officio, Columbia Titanium, and REI. Overall, I think Ex Officio has the best quality, but they are all pretty much interchangeable pieces of my wardrobe. I just take the one that is at the top of the stack of shirts in my clothes closet. However if they don't match my pants, and my wife catches me before I get out the door, she will make me wear a color-coordinated shirt. But the brand really doesn't matter that much. I don't take any of them on backpacking trips any more. If I needed to backpack in a long sleeve shirt with pockets, I would probably take the Rail Rider Madison River, with the Ex Officio as a close 2nd. The extra mesh in the side would be the deciding factor. By the way the Madison River is treated for bugs, but bugs don't bother me, I think it is against the law to have mosquitos in southern California.
We are really splitting hairs on most of these shirts. Most breath fairly well, and to me it is more of a question of function. I don't need pockets, and I don't need buttons down the front. For others, those items are important.
But the one shirt I will not wear if it gets over 80F is the Thorofare. It is a sweatbox.