Please help me decide either to go for a loan or an investment?

I just started a small international export business and i planned to make it as large as possible. My friends and relatives want to invest inn. However, am not sure either to let them invest and hold a share in the business or i should just accept their mony as a loan and pay them back with an interest? regardless the interest rate and the divident, my biggest concern is, which one will help the business grow faster as i plan to make it larger? Please let me know your thought and opinion on either to accept the money as a loan and pay them interest or i should let them invest as shareholders. Thank you for your contribution.