Definitely somewhere in between is my ideal.
I don't want a dog who will gladly go with anyone and be like 'see ya!' and not give a hoot about when they're going to see me next, LOL. But I don't want to deal with a dog who could be somewhat aggressive or reactive towards other people either.
Jackson is a bit too much on the shy side for my liking and it's the one thing I'd change about him. For the most part, it's aloof, but there is a touch of fear in there. He's okay with strangers in that he is very easy to take out in public. If kids want to pet him, they can, I just say 'go say hi' and he seems to understand. I wouldn't say he enjoys it but he doesn't mind, and tolerates it, and I wouldn't put him through anything he was uncomfortable with. He's more uncomfortable with strange men though and will shy away.
But he tends to just avoid being pet and prefers you not to say anything at all. He certainly doesn't want anyone picking him up (but, he barely likes ME picking him up, either). So if he thinks you're heading in for a pick up, he backs away quickly.
He's deathly terrified at the vet, but he's very good and just sulks, and completely shuts down which makes me very sad, but it's gotta be done sometimes. But he's not aggressive or a biter in any way.
Once he loves you though, he loves you FOREVER. He loves almost my whole immediate family even those he doesn't see very often (uncles, aunts, grandparents, parents, step-parents, siblings, close friends). But I love that he's still not totally obnoxious about it. But you can still tell he really loves you without him jamming into you, or licking up your nostrils, LOL.
So yeah on a scale of 1-10 with 10 being most sociable, I'd say he's probably a 5. Ideally, I'd like a dog with maybe 6 or 7.