Fuel type: Gas vs. wood pellets
Outdoor home pizza ovens mostly run on gas, wood or wood pellets. Propane gas pizza ovens can be connected quickly, ignite instantaneously and heat up in just a few minutes. They also burn clean, with less smoke and little mess to clean up. They can be hooked up to propane tanks in the same way you would a grill.
Wood and charcoal ovens, in contrast, must be loaded (and sometimes reloaded) with fuel before use and take longer to heat up; also, a consistent temperature is trickier to maintain. They also make a bigger mess, leaving behind ash and soot. Although you may assume wood-fired pizza ovens would impart a smoky flavor, the pies are not subjected to much smoke or in the oven long enough to absorb the wood flavor. The ovens do smell nice once they're fired up.
There isn't a significant cost difference among the various fuel types. It's more a matter of personal preference. Wood pellets can be purchased online or at most hardware and grocery stores and are available in a range of wood varieties.
There are also electric pizza ovens, including this pricey model from Breville and this new entry from Ninja. Electric pizza ovens only reach temps of about 700 degrees F. Purists may tell you that's simply not hot enough to make truly great pizza. We plan to test a few electric pizza ovens soon and will report back.
Size and portability
If you have a dedicated space for your oven, a larger, heavier model should work. If you'll be looking to store it away between uses or move it around regularly, a more portable oven is a better choice. At-home pizza ovens start at around 20 pounds, while semiportable and stationary pizza ovens can weigh several hundred.
Accessories
One accessory you'll definitely need for your new pizza oven is a pizza peel. This unique paddle-shaped tool allows you to safely slide a pizza in and out and rotate it for even cooking. Remember, these ovens get as hot as 950 degrees so you don't want to take any chances with a shaky spatula or tiny tongs.
The other accessory you'll likely want to invest in is a cover, especially if you plan to leave it out in the elements between uses. Some pizza ovens come with a custom cover, but many don't.
Cost and value
Quality at-home pizza ovens start at around $300 and go up (way up!) from there. More expensive pizza ovens tend to feature larger, sturdier frames, more oven capacity and they reach hotter temps faster. You can find cheap pizza ovens under $250, but so far we haven't tried one that's worth the investment.