Walmart carries them Danskin brand, which has some great sun shirts for around $10. I have them in multiple colors and lived in them all summer.
I am in love with the ExOfficio button shirts. It’s not a riding type shirt, but they are great for hot weather and they also work well as an overshirt, great for fall weather too. They’re nice enough to wear office casual. They come in colors and patterns.
Some of the sun shirts are clingy with a tight fit and some are looser. You may have a preference.
The knit shirts are vulnerable to snagging which is just something to be aware of.
I have shirts from Rompfh and Kastel Denmark that I like, not least of which because they come in colors other than white. I also have an UnderArmor shirt, which is a tighter fit but quite nice.
If you aren’t svelte, I recommend buying up in size when in doubt.
I put a couple of these shirts on the Christmas list (my mother gets upset if I buy things for myself after Halloween, says I am hard to buy for.) I also picked up some sun sleeves, on the advice of a friend at work. They seem to be working nicely. Like socks for my arms!
I’ve got Kastel and a Dover Coolblast Icefill. I like them both and find both options much better for me on hot days than any tank top or tshirt.
Of the horsey brands, I’ve been happiest with the Kastel shirts; I’ve got both the collared polo shirt type and the zip type and like both, and they seem to wash and wear well. The Haggerty’s I have looks nice, and I did a couple jumper classes in it, but like the other poster, I feel like the collar is a little wonky. I do love that I could pick the colors, though. The Noble Outfitters shirts I have are way too heavy for true hot-weather wear, but are fine in spring/early fall.
Of the regular outdoorsy brands, hands down, Patagonia. Look for their Cap1 or whatever they’re calling their lightest baselayer now. Silky, light, and last forever. I’ve also been pretty happy with the Columbia shirts I have. The SanSoleil ones are OK, a little heavier and less silky than the other fabrics.
