Single vision sunglasses are easy to wear but you can just use them to see either far or near only; progressive sunglasses can be used to see far, medium and near distance so they're quite convenient, but they need time to be adpated to. In my oppionion, you'd better get single vison sunglasses cuz sunglasses are usually used outdoors. HTH
Sunglasses are used to wear outside to block UV rays. Single vision sunglasses are only for far or near, while progressive sunglasses are transitions from near to far. If you have no problems focusing on near objects, I suggest you get single vision sunglasses which help you view distance clearly.
Progressive lenses are also called no line bifocals, they have all bebefits of bifocals and trifocals. They can ensure clear vision at all distances, for near distance, far distacne and also mid-range distance. For they have no lines in the lenses so they won't reveal that the wearer is wearing bifocals. Single vision lenses are for special purpose for one person to have one prescription to see at all distance. They can be used for "distance only" or "near vision" (reading only).