info taken from this site which sells a number of products... They've got a good chart with comparison of the choices.
"Frontline Plus for Dogs is a once-a-month topical treatment effective against ticks and fleas infesting your canine pets. Frontline Plus' starts to work upon application, spreading over your pet’s body, killing 98-100% of adult fleas and ticks on your dog within 48 hours of application. This rapid action also helps to control Flea Allergy Dermatitis, bringing fast relief from itching. Rapidly eliminating ticks also helps prevent transmission of dangerous tick-borne diseases such as Lyme Disease and Rocky Mountain Spotted Fever."
"Sentinel is an oral tablet that is used to prevent heartworm disease, control flea populations and adult hookworms and remove and control adult roundworm and whipworm infections in dogs."
"Heartgard Plus is a monthly medication for the prevention of heartworms in dogs. Heartgard Plus prevents heartworm disease in dogs by eliminating the heartworm larvae (Dirofilaria immitis) that infect the dog in the month before treatment. Heartgard Plus also controls heartworm infections acquired in the previous four months, provided monthly treatment is continued for at least 12 months."
(I will add that this product is ivermectin based and shouldn't be used on cats, nor collie type breeds --collie, sheltie, aussie, border collie--)
"Revolution for Dogs
* Highly-effective against a wide range of internal and external parasites
* Prevents heartworm disease
* Kills adult fleas including flea eggs
* Treats and controls ear mites and sarcoptic mange
* Convenient once-a-month topical application
* Safe for puppies from six weeks of age, pregnant and lactating females
* Water-resistant formulation
* Active ingredient: Selamectin"
"K9 Advantage for dogs is the "flea specialist" you need to protect your dog from these pesky parasites. Advantage works fast. Within just 3-5 minutes of contact, flea mouthparts are paralyzed, preventing them from biting your pet. Soon after that, it commences its lethal action, killing 98-100% of adult fleas on dogs within 12 hours of application, This brings relief to itchy dogs fast and is an ideal treatment for dogs with Flea Allergy Dermatitis (FAD). Female fleas on dogs are killed so quickly, that they are unable to lay eggs, preventing a new generation of fleas from developing. Advantage kills reinfesting fleas within 2 hours of attempting to hop onto your unsuspecting pet and continues to act for up to four weeks after application. It also kills larval stages of fleas in the environment within just 20 minutes of contact."
We generally use Frontline Plus and Heartguard on our dogs as it seems to cover them well with no reactons or skin issues.