I’ve been happy with my mid grade custom fit Carver cover.
Sun and weather exposure does take a toll, but flapping is what destroys covers fastest, so the more you keep it taut, the longer it will last. Also, try to keep it clean, and hit it once or twice a season with Star Brite or 303 waterproofing spray. Use enough support poles so water can’t pool on it, then everything under the cover will stay dry.
It takes a bit more work, but if you rig the straps so they go from one side of the cover under the boat to the other side of the boat, instead of to the trailer frame, it will keep the cover tighter and allow less air underneath, which means the cover will flap less and not be as stressed when the boat moves/bounces while trailering.