Lets assume a few things first.
That you have the cash you need,
that you have a license,can and will obtain insurance
and have all the riding gear you need.
Now, how do you plan to use it most of the time ?
Daily commuter on surface streets ? mostly highway ? touring ? occasional trips to the strip ?
what matters most to you ? looks ? performance? mileage ? comfort ?
no one bike covers it all with all top scores.
You have some experience that's good.
Going by your attraction to the 250 ninja its fair to assume you like the sports side of things.
Consider a Suzuki GSX F 650
Looks sport, sits standard,good compromise between too small and too big.