Should I buy insurance from friends or non-friends?

It depends on your relationship also. typically you need to provide your financial information to them and some may not be comfortable. but no matter what, you cannot be paiseh to reject if you don't feel it's right.

I personally bought insurance from a close and good friend. She didn't start out selling insurance and only switched over after a few years of working.
I feel that if you buy from a non-friend agent, they might try and earn money from me more (as non-friends will not mind losing me as a connection). If you are worried about being difficult to reject your friends, maybe can take the chance to be more thick skin? Or at least that's what I do. If I feel that the plans are not what I require, I will just reject.

Whether buying from friends or non-friends it doesnt matter. what matters most is that they are able to provide you with what you need.
if you are afraid of rejecting them, maybe you can say in a subtle way that this is what i need now, and if i ever need more you will look for you.

Do what you want. There's no way for us to tell you which is better.

But it's easier to speak to friends when you have a problem, though it gets sensitive if they are not professional enough with you.

So end day, it depends on how comfortable you are disclosing your finances, goals and problems to either a friend or a stranger. Whichever you feel more comfortable with is the one you should go for.