How should we structure this company?

If you have an LLC, you can easily separate the division of profits from the division of control.

E.g. A and B can have 50-50 control, but A can have a 66% share of profits.

E.g. A and B can have 50-50 control, and 50-50 share of profits, but each get paid an hourly rate. So if A is working more, A gets paid more.

Ah, and I just noticed you are "Person C". Are A and B the only players here? If not, it changes the ratios but not the fact that profit and control do not have to be tied.

Your LLC operating agreement can protect a minority owner by having some rules that require a majority of the members -- not a majority of voting units. Or it can require unanimous consent of all members, e.g. you can't dissolve without consent of all owners.

Your lawyer will set you up with a buy-sell agreement. This will outline the conditions under which you can sell ownership interest to new members, and under which a member can leave and potentially sell ownership to another member or a third party.

A good lawyer will ask you a lot of questions about which way you want to resolve certain of these options. I would also recommend one of the "How to form an LLC" books that discuss all of these things -- a good $30 investment even if you have no plans to DIY and are going to use a lawyer. It will make it so you know what the lawyer is talking about during your visit, and could reduce your legal bills by making the process go more smoothly.

I'd go for 50/50 with a buyout clause that uses exact numbers for at least, say, a three year period from commencement. It's potentially a lifestyle business, or it could go further. The two parties are both vital, the two together are sufficient, there's trust, and there's no way to guess which is more or less likely to stay the course. A fixed buyout schedule allows a graceful exit in the most likely negative cases. And in the success case, it's simple to remove: that's why a fixed schedule is important, so that when both parties see far more value in the business than the schedule implies, the buyout becomes moot (if A and B both offer, neither can enforce). Save the legal complexity until you need it: for instance if at a later date you need to raise money. At that time, clean and simple structures are worth their weight in gold!

I would worry more about developing your products/services than about the legal structure of the organization. If A and B really get along, they'll figure out a way to work together. Team work is the basis of any organization regardless of the structure.

Plus, there is no legal structure that fits perfectly in any organization because when you actually set up your legal structure you don't know what's gonna happen in the future.

Of course this is not to say that you shouldn't pay attention to the issue, but as a businessperson I think you and your team should focus on developing high quality products. The rest is secondary.

Good luck.