1. Keeper 07203-1 Waterproof Roof Top Cargo Bag (15 Cubic Feet) (Click Link to Check Price on Amazon)
Editor's Rating : 8.8 out of 10
Waterproof rooftop cargo bag with 15 cubic feet of spaceIncreases vehicle cargo space

2. OXBOUND Roof Rack Cargo Bag - Waterproof Car Top Carrier (15 Cubic Ft) + Free Protective Roof Pad Mat and Free Storage Duffel (Click Link to Check Price on Amazon)
Editor's Rating : 9.1 out of 10
100% WATERPROOF MATERIAL - We chose the highest quality material to protect your gear and luggage from wind and weather on the road. MEASURES 37.5" x 37.5" x 18"BEEFED UP STRAPS & BUCKLES - Many existing bags have thin straps and tiny buckles. We created bigger buckles & thicker straps to ensure greater strength and security when attaching the bag to your roof rack.

3. G4Free 18.5 Cubic Feet Waterproof Car Top Carrier, Easy to Install Soft Roof Top Cargo Bag with Wide Straps-Works With or Without Roof Rack (Click Link to Check Price on Amazon)
Editor's Rating : 8.8 out of 10
Large Capacity: 18.5 cubic feet Dimensions: 55 (L)x 37(W) x 15.8(H) inch

4. SHIELD JACKET Waterproof Roof Top Cargo Luggage Travel Bag (15 Cubic Feet) - Roof Top Cargo Carrier for Cars, Vans and SUVs - Great for Travel or Off-Roading - Double Vinyl Construction, Easy to Use (Click Link to Check Price on Amazon)
Editor's Rating : 9.2 out of 10
Spacious Roof Bag: Whether you're planning a cross-country trip or you're in the mood for a little off-roading, our roof top carrier is ready for any adventure! Great for cars, vans or SUVs with roof rack systems, it provides 15 cubic feet of convenient, secure storage.Completely Weatherproof: Our cargo carrier is ready to brave the elements! With welded seams to seal out water, it's totally weatherproof and protects your gear against rain, grit, snow, wind and sun. Ideal for family road trips, it increases the space inside your vehicle.

5. Ohuhu Upgraded Cargo Carrier Bag Hitch Tray Roof Top Cargo Bag Rain-proof , Fire Resistant, 15 Cubic Feet (Click Link to Check Price on Amazon)
Editor's Rating : 9.9 out of 10
EXTRA LARGE CAPACITY: This bag has extra large capacity with 15 cubic feet to store and protect more than you can imagineWATER & FIRE PROOF: The bag is constructed from premium high-quality material, which is, rain proof and fire proof.ATTENTION:under heavy rain wrapping the cargo bag with a plastic bag is suggested due to the small gap on the zip part