There's a lot of Ninja 250 fans here, but I'd suggest going up to a 500. Plenty of power, should get you going quickly without topping out too low for highway speeds. I don't find a huge difference in the 250/500 prices, at least out here in the West.
I'd suggest going to a dealer, and sitting on all the bikes. See what's comfortable for you, then look for a used bike, unless you find the perfect new one.
I'd suggest going to a dealer, and sitting on all the bikes. See what's comfortable for you, then look for a used bike, unless you find the perfect new one.