I've tried a couple brands, and thus far my F.O.A.L. shirt is a favorite, but it is on the thinner/sheer side since it's made for warm weather.
I would really recommend the Essex Classics Fitted Coolmax Wrap Neck Show Shirt. It is a little more expensive than the standard show shirt but can get great use out of it. I would recommend the white for a clean and classic look. The shirt is cool max and allows great ventilation. The color is the snap buttons which I am obsessed with because it does not give you that chocking feel when you are going around the ring :)
I would highly recommend Kathy Williams Double Collar "Tails" shirts, here's the link: https://www.facebook.com/kathytails/ or Show Diva Designs fitted shirts: http://www.showdivadesigns.com/fitted-shirts
I hope it helps you :)