I like these big chunky ones like Sprodomantis because I like to hold them in my hand once in a while and they are tough buggers that don't easily die in captivity.
When it comes to collectors items I'm a Empusa fan. They're the closest thing to my idea of what a mantis should look like.
I'm currently in love with Java Shields. Beautiful, spunky, and easy.
But I do have a soft spot for Chinese too. Something about watching a huge mantis molt into something even bigger, and take out a roach nearly as big as itself, is awesome. Course I've always been partial to sharks and tigers too.... Something about big, tough predators is thrilling. Creepy, I know.
I have to say my new favorite is the orthodera minstralis as I think i have some but they came from new zealand anyways and also liked the gambians and shields but theres other species I like but would love to actually own or have some parymenopus davisoni mantis or try again with thistles or orchids!