Roundup 5005610 Weed and Grass Killer Concentrate Plus and Compare-N-Save Concentrate Grass and Weed Killer are two effective weed killers that receive high ratings on Amazon.com. As of 2015, Roundup 5005610 is the best seller in Amazon.com's Weed Killers category, and boasts a rating of 3.9 out of five stars.
Compare-N-Save Concentrate has a higher rating with 4.5 stars on Amazon.com, but has nearly 70 less reviews. Compare-N-Save advertises visible results within two to four days and covers over 25,000 square feet.
Roundup advertises visible results within 12 hours and is effective on driveways and patios, as well as lawns. It guarantees to kill all types of weeds at the root and offers a replacement product or full refund with proof of purchase if the customer is unsatisfied with the product or its results.