Please, may I be a heathen here? Or at least show my age?
IMO, the ideal first bike is either a Yamaha 650 - one of the old uprights, or if you're tall enough to handle it, a Honda CX500 twin. Enough power to get you on the highway, Reliable enough to where you won't have many problems (and easy enough to work on wthat when you do, you learn how to fix them, adding to your edumacation!), super stable, and cheap enough so when you whap it into something (and yes, you will scrape the sides and do other stuff) it's either easy to fix or cheap enough to where you won't be crying you killed your wallet when you have to let it slide away from you and into that light pole.
Sure, they're old (which means you can find them on craigslist pretty easy). But they're also cheap, and it'll be less of an outlay for a "learners" bike. Also, instead of being crouched over a bike and being forced to look up, etc, you're already upright, and is easier to find your balance when green.
I used to recommend the old CB450 twin (and have taught a bunch of people how to ride on one), as they were light, could be set up to haul, they almost never broke, and when they did an idjit could rebuild them on the road, but parts (hell, the bikes) are getting pretty few and far between.