Profit Sharing with Investors

Need suggestions on how to fairly split profits with investors.

I am considering starting a marketing consulting business, using a proprietary
business model. The owners of the model are charging USD$40,000 as a "franchise
fee". I would like to get started by finding one or two investors to put up the
$$, and then repaying them from the proceeds of the business. I am in the US,
but do not believe that this is important to the questions.

I will be doing all of the work in finding clients, selling the service, and
providing the solutions. The investors will not have to be involved.

What is an equitable distribution? Should I set up the contribution as a loan,
and then, once it is paid off, be done with the investors? Or should I
structure it as an equity participation, with the investors receiving a
percentage of the gross (or net) profit for a specific time (or in perpetuity)?

I understand that I CAN do any of these things, but what is most "fair" in your
opinions? Philosophically, is the person/entity who puts up the funding that
allows  a business to begin entitled to the same compensation as the person who
actually does the work?

Thanks!

Tony