I would have used Hardipanel T-111 much easier to paint and no rot. Since you went with wood I'd use a opaque stain with a very heavy roller. You'll still need to brush the grooves unless they are very shallow. As to brands any premium would do. I tend to use Sherwin Williams for exterior paint. Rough sawn T-111 is a bear to paint. Been there, done that. Hardi gives you the look, but is smoother and takes paint beautifully.Gentlemen, I just had a cabin constructed with T-111. What would be the best protectant for it and what would be the brands name. Thanks.