I am only 21 year old but can certainly agree that both have their pro's and cons, it all depends on where you are at with your life and your circumstance. I'll give you a brief layout of my experience just to add more to this thread.
I was a socially awkward boy in highschool and the couple of years afterwards. I still had my V-card and only kissed a couple of girls. Being single sucked and I was pretty lonely. Then along came my GF which was A LOT better than single. I had a lovely companion and regular sex. My needs were being met and life was good.
Fast track a couple of years to now. It's getting hard to keep things fresh with my GF. She has constant problems too which is hard for me to deal with. It really is holding me back, but thinking of it makes me feel guilty. I just want more! I have been craving the single life more and more recently. On another note my confidence has increased dramatically through hard work and dedication. I am pretty popular in my work place which is a vast improvement to a few years earlier at school. I am twice the man I once was.
Very recently, my work just had a Christmas party. All the stores in the state, we're talking a few hundred strangers packed into one massive nightclub. Girls were trying to get with me left right and center. It was fucking awesome. It was good to have some validation that my confidence and maturing had made such a difference. I wanted to hook up with them so bad. I wanted to do what I had always wanted to do. My inner caveman ached to burst free, but of course I kept telling myself, NO. Eventually it happened though. A gorgeous red head. I knew what she wanted but just decided to dance with her, trying to avoid her eyes staring up at mine. Eventually she had enough, grabbed my head and laid a smooch right on my mouth. She looked at me with a look of "Thats what I wanted and I fucking got it". She turned to move away but the inner caveman had broken free. I grabbed her and locked lips with her. We sucked face like mutant tongue monsters for a little while before I moved on. It was better and more passionate than with my GF. I went looking for her again later but couldn't find her. I just wanted more of that experience. I wanted to kiss her again, I wanted to taste her cunt. My primitive masculine side had been repressed for so long but now it was out.
I don't regret it. For the first time I feel ready for the single life. I want it so bad. But alas I am in a relationship with a girl whom although has her problems, I will never find a girl anything like her. I don't know what to do.
Both single and committed lives have their pro's and cons. For everyone I imagine these things will become apparent in different ways. I think it is important to experience all of it, so you can become sensitive to your needs at each stage of your life.