Wow they are young aren't they!
Orchids rarely eat prey that isn't flying, so unlike other matids you can feed crickets, roaches, locusts, waxworms etc to, orchids you need fruitflies for nymphs and green/blue bottle flies for adults, you just buy a pot of maggots wait until they form a cast and chuck a few in the mantids enclosure
Out of the 3 you mentioned, i'd deffo choose a peacock, in fact i have on myself, but out the 3 you chose, peacocks are the easiest to keep alive and care for, room temps fine, they eat anything and everything and its uncommon to lose any few at one time for no apparent reason! theres loads of lovely looking easy to care for mantids...but so many people are attracted to the flower type as well as dead leaf, ghost and gongylus species, but again they are slightly more difficult to care for, all differ....but i'll stop babbling now and just say...
Lovely manties!!!! :mrgreen: