I have used both. Hard money will be the most expensive, but the most emotionless. Its all about the numbers and the deal. Even though its more expensive, you should know those costs up front so simply underwrite those into the deal.
Friends and family can be tricky. Its really a case by case basis with that specific person. The best advice I can give is make sure everything is on the table and understood up front. Put this in writing. whether its officially recorded or not, at least have it documented on something you both sign. I even did this for a private money loans with my parents.
Make it clear up front
1. the term you plan on borrowing for
2. what it will be used for, including property address
3. payment and interest terms
4. end game or exit strategies
5. what the borrower and lenders role is (lender vs equity partner)
the last 2 are important to preserving a relationship. have plan up front for if things go wrong. also, make sure they are aware they are a lender, not equity investor on the property, and you control all aspects of the project. in return they get a steady return.
private money from friends/family can be one of the best sources of capital, but you have to understand the person you are approaching. i have very close family members that i would never ask to lend because i do not want to jeopardize the relationship based on their personality. The ones that i have approached, i knew trusted me absolutely.