I asked DH about this as he has taken good care of our vehicles, tires, etc. IMHO <3
His advice (talking to me who knows nothing about this) was to purchase the best trailer tire you can reasonably afford. He stated you would do best with a 3 ply or 4 ply tire with good treadwear (the higher the better). He checked our new Roo and was pleased (not!) that they were not what he would have bought, but they seem ok for now, will watch them. He also treats the tires and keeps them covered to reduce dry rot. He also agreed that you need to check the tire pressure each time you leave for a trip.
He mentioned liking Cooper tires, overall, but didn't know if they make a trailer tire or not; didn't seem to have a preference as to a brand of trailer tire. He still avoids Firestone.
Blow outs are scary, I'd be freaked out too......