At 99 range and other max stats, you could easily duo or team any gwd with pretty cheap gear. I would go to bandos first. After a bit of experience, If you have a friend or two that can show you the way, and 70 Agility then I suggest armadyl, as it has the best item drops. Saradomin is a very good option too. Zulrah, if you have void is also a great way to start bossing, as it is technically safe, as you can talk to a man, and he will give you all your items if you die and lose them