The main reason I wanted to use the jars is because they seem large enough to provide a small mantis with enough room to molt and move around...plus, I get them for free (most of the time) from a local restaurant. Even if you buy them for the pickles, they are still cheaper and more suitable for mantids than the fancy gallon jars sold at department stores. Seems to me like an economical way to raise a fair number of mantids.
I agree with the previous comment about clear containers: most mantids like bright lighting.
Another container I've considered: a ten gallon tank divided in three with plexiglass and aquarium sealant. Only trouble is the mantids may see one another through the plexiglass and get stressed. Any thoughts on this?