There is no such thing as a communal mantis. There are a couple of species that are less agressive but over all they are canabulistic. I would recommend going with Chinese Mantids as a first species. They are hardy, common and very cheap. I am currently raising many L3 nymphs. They are fascinating and growing like weeeds.
I was just thinking about getting a mantid as a photograph subject aswell as a great pet, and was wondering ( apart from apperance and all) which are the lease skitty, and most calm when handled. So that they will stay in one place for a photo.
I would go with the chinese mantid. They are not skittish at all. They love to sit on your hand or wherever and just watch you and whats going on around them. Their size, stature and demenor make them excellent pets and photo subjects.