I try to do both. It's important keeping the balance. But it's very important spending time with others, we need human contact as much as we need the company of ourselves once in a while.
It depends on the persons personality. Some people like partying some like quiet nights. You need some social interaction with other people or else you go craazy. But it all depends on you and your own personality to if you prefer alot of friend interactions or time on your own. For me I prefer other peoples company unless I am feeling abit down in which case I prefer to be left alone hah.
A little bit of both can help. For example, let's say you hang with friends at school, well I guess it can be alright to be alone for a few hours at home. But, spending too much time a lone is not healthy. Nor is too much time with Friends that, your completely separated from your life at home.
Interaction is good, solitude is bad because eventually you'll feel loneliness and succumb to depression. However, interacting all the time isn't good, you need a bit of solitude to free your mind.
Well, since I don't technically have any friends, this would be a silly thing to ask. But I tend to think a lot, yes. However, I dislike going to parties so I guess I would like to spend my time alone. Yet, I feel like being all alone... Is scary.
Solitude is necessary when you want to introspect. It's like cool spring breeze that follows an oppressive summer heat. I usually prefer to stay alone. Ironical, though, that if your lonely all the time you'll eventually yearn for friendship. So, I suppose both things in adequacy make a good combination.