All American. I have an All American and a Presto...I like and use them both, but the metal-metal seal in the All American means you'll never be stuck trying to find a replacement gasket. Got both of them from Amazon.
If you're just starting out in pressure canning, consider eventually acquiring at least 2 different sizes...that'll keep you from having to shortload a bigger canner with a small batch of whatever you're canning.
My Presto is a 21 qt, and the All American is a 30 qt., and I wouldn't mind eventually picking up a 10 or 15 qt canner for some things. As previously stated, the All Americans are way more expensive, but will last several generations as long as you're doing your part in keeping it up!