She's not my best friend?

I need some random opinions here:

I have been with my girlfriend for over a year. I'm 36 and have a young son from a 13 year relationship that started in college. I'm constantly looking at where I am in life and I feel like it's time to move forward with her or move on without her. If this decision was a no-brainer, she'd have a ring on her finger. It's not that easy, so here I am:

I know it's not fair to compare her to those in my past, but we base a lot of what we do in life on experience. So share with me some of your experiences and what you think...

She's not my best friend. The ex-wife and the last woman I dated were. I don't know if that's really how it's supposed to be. I have a core group of friends from my younger days, from work, from my church community and from other activities in which I participate. I have family nearby and we see each other often. She mixes well with most of the people in my life. She says I'm her best friend. I can't say the same about her. It hurts her that I don't say the same thing. I'm not going to say it just to make her happy if it isn’t true.

My question and explanation could easily be pages long. I love her. There are many things to love about her. There are a handful of things she does and says that annoy the hell out of me (sounds like we're married already). Is it a matter of loving her, but not being "in love" with her? Possibly so. She doesn't drive me crazy. She doesn't consume me like others did in the past. I don't miss her when we're apart. I feel like a jerk for saying it, but it's true. There were certain traits I miss about those from my past. These are tastes and characteristics that my girlfriend seemingly will never cultivate. For each of those traits there is another that she displays that nobody from my past has shown.

Thinking like that makes me think the perfect person for me is a combination of her and my exes. If that's the case, would I be settling for less if I stayed with her? In reality I know I'm trying too hard to analyze things mentally, when this is a matter of the heart.

I’m done rambling. Should my significant other be my best friend? If so, I'm not in that situation. If I could put a ring on her finger today, I wouldn't. Should I just cut things off? What would you do?