You may get more diversified answers than you need. My personal favorite for your specifications, although I haven't tried the azureus yet and am just getting my first leukomelas next month, would be the pumpkin orange (splash back) D. galactonotus. They are bold, active and amusing. The red form is very expensive and more shy. My blue auratus are especially shy and retiring, but this may only be the particular color morph and breeding line. They are hardy enough, but one wants to see one's first frogs occasionally and not have to hunt for them to make sure they are all still alive and feeding, or feel like hiring a frog psychologist for a consultation.
Don't be put off by the size of thumbnails like vents and imitators. They may be tiny, so a bit scary, but mature faster and breed sooner than the big guys, and are just as bold in their miniature way--actually pretty easy to keep and great fun to watch as they go about their froggy business.
You are obvously one of the people that are going to be thoroughly prepared ahead of time. That's great, and that is what will make you succeed with just about any of the recommendations you will get from us.
One warning: You will catch a disease from your very first frogs, and that's an obsession with them. It's not fatal, only chronic.
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Patty
Lost River, Idaho