You've been through the games once, so you should know what to expect in each area and have a decent understanding of game mechanics. Perhaps a Mesmer might be up your alley - you're forearmed with the basic knowledge needed to play them effectively.
Although you could just as easily do a series of coin flips for choosing your next xharacter's profession. All of them have something different to offer and you'll always have a minimum of 8 character slots if you have all the games, so you may as well experiment with all of the professions to see which is the most fun for you
