Are 400cc or 500cc bikes still relatively forgiving bikes for new riders? Are older 600cc bikes more forgiving than more recent 600cc bikes? I've seen the sv650 recommended alongside the ninja 250 and even the classifieds advertise the sv650 as beginner friendly and cheap insurance. This is confusing to me because I read everywhere on the forum that beginners should never go above 250cc.
Why is the sv650 or old 600cc models an exception???
What is relative is completely dependent on what your experience on 2 wheels is. If you have none, even a 250 will scare you, until you learn how to control it. Take a course if you haven't already (they usually provide a bike for you to play with). If you can master your own urges to speed dangerously, learn to use the brakes progressively and learn complete control of your clutch, then go ahead and get (almost) any bike you want. I started on a 600ss, loved it, glad I didn't go smaller, after a couple of years I moved on to something a little bigger. Since you didn't mention anything about costs I won't even delve into that. Whatever bike you do get, I suggest a lot of safe practice in a empty parking lot, with braking (emergency braking as well), clutch drills, and just get used to your bikes abilities before going on long rides and putting yourself in a bad spot.
Good luck, hopefully you find what you are looking for.