There are two basic types of crate: plastic and wire. There is also a third kind which is less common than the two called a soft mesh crate. Which of the three is the best? That solely depends on your environment, lifestyle and doggy.
1. Plastic crates- it feels more like a den because it's cozy and closed in three sides. It will keep your dog warmer and protect him against drafts during the cold.
If you're fond of travelling, only plastic crates are allowable in cargo. The two other crate types to be mentioned below is not allowed in the plane's cabin. A plastic crate is also considered the safest way for your doggy to travel in a vehicle.
Unfortunately, due to it being closed, it can hold more heat. If you live in a tropical country like I do, a plastic crate is like a tiny oven during the hottest days of the year. Unless your house is air conditioned, you should consider the second choice.
2. Wire crates- I personally prefer this type of crates because I like bringing my old dog outside. The inside of the house is very hot and the outside is, as well. The only consolation of staying outside is the breeze.
Wire crates allow more ventilation. It also usually has a removable tray at the bottom for easy clean up.
This is Buchi in his second crate. I can't wait to take a picture of him when I visit him next week. Since dogs couldn't run free in my sister's neighborhood, he stays in a VERY big cage.
Although my crate did not have an adjustable panel (to make it fit for a puppy), most wire crates nowadays do.
Here's a collapsible wire crate ideal for traveling. It even has an adjustable panel for puppies.
Wire crates aren't snug for dogs with little fur. If you do buy a wire crate, consider purchasing its crate cover. You can also make use of blankets or towels to cover the top and three sides of the crate to keep your dog cozy when it gets cold.
3. Mesh crates- This crate can be folded compactly and is lightweight. The reason why some people use it is because it's easy to store especially when traveling.
People with competing dogs usually prefer mesh crates because of the reason above. It is also easy to carry and set up. They also give good ventilation which is important because dog events are most of the time packed.
Finally, before deciding on what crate to get, don't forget the basic rules in crating. Here are some of my Do's and Don'ts for reference.