Should I go through an adoption agency or choose the private adoption option?

I am currently pregnant with an unplanned pregnancy and I am looking at the adoption option. I want to provide my baby with the utmost care since I am unable to care for it. I wouldn't really mind going through an agency but it seems that the mother wouldn't get any advantages, like picking out the family, "honest" open adoptions (what if they dont keep in contact?) or you cant get money through an agency. I hear that some agencies may help with living expenses and education but what about people who want to adopt privately? how does that process take place and would you get any "better" advantages that way then with an agency?