Impossible to say, you'll need to call around to all of them as there is no perfect answer.
At 18 with no driving history and new to motorcycles your options will be limited though, many insurers will not insure you.
Your choice of motorcycle is important as well - if you intend to buy a supersport plan on paying through the nose...if you can even find an insurer that will take your business. Choose wisely - SS's are not beginner bikes.