Chain Slip Collar: This type of collar is very simple to use: All you have to do is pull the leash to the side. BE CAREFUL NOT to pull too much this type collar chokes your dog until you release, but it may stick at times.
Martingale: We use this type of collar on Mason (My Maltese-Poodle Mix) It is similar to the Chain Slip Collar Except it has fabric on one side and the other is chain. You much pull to the side to correct the dog.
Head Halter Collar: This type of collar actually goes over the dogs head. If you or the dog pulls at all, the dog will turn towards you and it closes the dogs mouth. Dog trainers usually use two leashes-One for the Head halter, the other for the collar. Doing it this way usually give the owner more control. It does not prevent the dog from biting. The head halter is not a muzzle.
Harness: This type of collar is used on the actual body. It gives you more of a control of your dog and doesn't put pressure on the throat. Some dogs will try to back out of them and some dogs bodies do not fit this kind of harness. We've bought some harnesses that do not fit my dog Mason Correctly. You may want to purchase a custom-made harness.
Regular collar: Darcy(My Shih-Tzu) uses this type of collar. Any dog can use this type of collar, but it is recommended for dogs who do not pull on the leash.
Microphone/Talking Collar: This type of collar actually has a built in speaker. A person has a microphone and the sound comes out of the speaker on the collar. This is a great tool to use if your dog chews on things while you are gone.
Collars I Despise
Prong Collar: This collar is complete torture to a dog. When the dog or you pulls the leash it causes the spikes to stab through the dogs skin and can embed itself into the dogs neck. Would you put this collar around your neck?
Shock Collar: This collar gives off a shock wave to the dog with the control of a remote. Anyways it makes your dog afraid of things. How would you feel if you were zapped every time you made a mistake?
Dog I.D Collars: There is not any torture with this collar. The only problem with this collar is that it shows your dogs name. Imagine if someone broke-in your home. All the person has to do is call the dogs name and He/she can lock your dog in a room while they steal your things.Someone could easily steal your dog. Would you want someone to know your name that you don't know?
Citronella Collar: This type of collar sprays Citronella in your dogs face when they misbehave. At times it may spray the dog when they are doing nothing wrong. Would you want some kind of spray to squirt in your face when you don't do anything wrong at the moment?
Flea Collars: This collar controls fleas from your dogs neck. It doesn't protect dog's whole body. It also does not kill the fleas. Sometimes the collar have too much flea medicine in the collar which is not good for the dog. Would you like a collar that has too much or too little flea medicine around your neck even though it doesn't completely repel fleas?
TIP: When putting a collar on your dog, there should only be two finger lengths in between the collar and the collars neck(And body if you use a harness.)
The above is only my opinion about the different dog collars on the market today.