Asian giant mantids, robust, fast growing, and the practical starting point for anyone getting into mantids seriously.
They take large prey, grow through instars quickly, and are forgiving of temperature and humidity variation in a way the more specialized species are not. Species identification in the trade is loose, with several regional forms sold interchangeably.
Mantids all share the same market shape and it is worth understanding once: they live under a year, so every purchase is a short commitment, and the market has to fully repopulate itself annually. That makes prices low, availability seasonal around breeding cycles, and adult specimens a poor buy relative to nymphs.