Buy Japanese and buy the newest, best example of whatever floats your boat. Between the Big 4 there's not much to go wrong. Bear in mind that your consumables (tires, chain, brake pads, maybe fork seals) can easily add up to several hundred bucks if you need to do them all at once. Again, buy the best you can.
SV's are great starter bikes, and I'd suggest you save up for a good example of an early one. That's a bike you can learn on comfortably, and you can modify it to perform better as you become a better rider. They will be popular in amateur racing for many years because they sold so well, so you won't get left out in the cold for parts in 10 years.
Personally, I'd avoid any Yamaha older than the '90s, only because their parts tend to get really expensive when you go older than that. Dunno why, but that's just the way it is.
Don't forget to budget for gear. There's good stuff available at low prices these days, but for a boots, jacket, gloves and a helmet, you'll still be looking at around $300 if you buy new. (Look at Sparx helmets; they're fantastic for the price.)
Best way to carry a backpack's worth of stuff is...in a backpack. I highly recommend an Aerostich courier bag. The big one. Yes, it's expensive, but you won't need another one for at least 10 years. Seriously.
And you know, we have a Sprockets forum just for this kind of question...