I have been both. Each has it's own benefits, but I believe being the youngest person works best for me because I am mature for my age, I can blend in well with those older than me and they generally don't realise how young I am, or soon forget it. However, with a group that is younger than me I would usually become the mentor/parent/counsellor, and while I don't mind this role, I prefer being with peers.
I already am the youngest person in the group :P
I have been both. Each has it's own benefits, but I believe being the youngest person works best for me because I am mature for my age, I can blend in well with those older than me and they generally don't realise how young I am, or soon forget it. However, with a group that is younger than me I would usually become the mentor/parent/counsellor, and while I don't mind this role, I prefer being with peers.