Clear, weather resistant coating

Submitted to Product Chat

My wife makes signs as part of her crafting hobby. They start out with wood cut from boards and she uses vinyl lettering she cuts with her Cricut. I've told her she needs to seal everything for outdoor protection from the elements. I think should would get her best results using a spray. But what would give the better protection? It comes down to Varathane Spar Urethane or Rustoleum Painters Touch 2X Clear. Painters Touch would be more economical if that would work as well.