EB,
The order of preference would be ceramic crock, then glass jar, then food grade plastic.
I asked for a Harsch crock for my birthday a few years ago since they're soooo expensive - around $150 - but worth it. The 10L (2.6 gallon) is the ideal size for most home uses. I don't remember exactly where we got it but they're virtually all the same price. Very heavy so make sure shipping is included.
HERE'S A LINK to a site called the Canning Pantry so you can see what they look like. I'm using it for sauerkraut right now but it works great for brining pickles in the summer. The 2-part weights keep everything weighted down and the water sealing system around the top lip is genius. You fill the 'moat' with water and it creates a one way seal - the fermentation gases bubble out but it keeps mold and other airborne particles from getting in.
Another ceramic option for about a third of the price are
THESE STONEWARE FERMENTING CROCKS. Lehmann's sells wooden lids and weight boards as well. But you can use a plate and a jar of water to keep everything submerged. Just drape a clean towel over top.
For some reason, that I honestly don't understand, the stoneware seems to inhibit the growth of the unwanted molds and yeasts. It could be because the crocks keep things dark while glass and plastic allow in light.
My second choice is glass - works almost as well and way less expensive. Hardware stores and even Dollar Stores have 2 gallon glass jars available at this time of year. Sometimes full of olives or candy or even empty. If you have an Italian restaurant in your neighborhood - they may even be throwing them out. Otherwise go to the canning section of the hardware store or the supermarket and get the Ball glass jars. The 1/2 pint glass jars fit into the neck of the wide mouth jars so you can use those as weights.
Or if you'd like a similar hassle-free airlock system you can get
a LID LIKE THIS ONE which has a built in airlock that you fill with water.
Homebrew stores carry a lot of this stuff as well.
I avoid plastic for no other reason than it kind of icks me out. It could be perfectly safe but I don't like the idea of acids and plastic and food all co-habitating for long periods of time.
Michelle.