Are you tired of all of these naive and impractical attempts at peace? Do you revel in the glory of battle? Do you see chaos as an opportunity?
Then your choice of god should be obvious.
The truth is that we're at war. Like it or not, everyone is going to be involved soon: Every god, every faction, every kingdom with any kind of military. You're going to fight whether you like it or not, so you may as well join the strongest side: Bandos's horde accepts all.
Perhaps the strongest piece of evidence for this is that the god himself is different. The likes of Saradomin and Zaros see you as tools to further their agenda, wanting to rule you because it's their right to do so and feeding you lies about your importance to them. While Zamorak's goals are admirable, he himself holds the honor of being as strong as the God of Cabbage: clearly, he was not strong enough to take advantage of the chaos he loves. Armadyl is perhaps the most hypocritical of all, starting a war in the name of peace. A pacifist whose name is attached to some of the most feared weapons on Gielinor. Bandos respects your right to use your hard-earned power as you please. Armadyl would force it at sword-point.
Only Bandos sees you as an equal, and the strong are rewarded. It's survival of the fittest in its original form: the winners reap the rewards not through physical power, but through adaptability and intelligence. Most of his own followers are deficient in one way or another, and so are good for little else than entertainment: a fact that you're very familiar with after slaughtering his followers when you were too weak to use anything more than a bronze sword. They're physically strong, true, but can't think for themselves, and can't adapt. You, on the other hand, while physically weak, have invented a weapon capable of fighting a god. For that, you've earned your place among his elites. If the other gods could do so, he would say the same of them: as it is, all they've been willing to do is talk and plan rather than act.
In this regard, Bandos is nature. We label the god as evil for encouraging evolution, for keeping those who are supposed to be our betters from becoming too weak to rule us, be they man or god. Armadyl would have you use your strength to strengthen the community instead of the individual and cooperate with those who cannot survive on their own. You don't have to look any farther than the world event to see how well this works: Armadyl has numbers, but his followers barely contribute to their own war effort beyond their daily cap. Bandos's forces are more devoted and better organized: when Bandos wants to claim a spot or disrupt a caravan, very little can stop him. Armadyl's followers know this, and many choose not to fight at all rather than face certain death.
Hiding from the natural order does not make it go away. Such complacency only encourages weakness.
You can fight for a high ideal such as peace or justice, or for profit, or for the joy of battle. It doesn't really matter: you could even fight for a different god in another war. As long as you fight, you're supporting Bandos. Do so openly and reap the rewards.