Expanding family!

I have the option to either be a mentor (kind of like big brother big sister) to a kid in foster care, a weekend family (where I could bring them home one weekend a month, or an adoptive parent and have them all the time and be their parent. They are school aged and teens. I don’t know which route to go and am wondering if anyone has any suggestions? I’ve been a mentor before and would definitely do it again but I also want to be a part of their village and be family. I’m a little confused on which route I want but know I want to go with one of these options.