I choose 37. Two years ago I had just moved into my house, was financially stable, and pretty happy all alone with my house and my doggies… Now I am supporting a parasite ( also known as my brother) , and very broke due to said parasite and his child, and I am no longer alone.
I loved living alone. I loved having money. I loved 37.
11, 12, 13 – with all those neighborhood verse neighborhood baseball games. The friendly “wars” we had in the woods using tree forts we built ourselves. Being almost totally spontaneous in all that I did.
I should note, that the “Do not use 4ever rule” does not apply to Prince, who transcends all such rules, and makes very good pancakes, to boot. 
As for the topic at hand, I’ve often thought of this question, and decided that, if all my other friends would do the same, I’d love to be 4 years old. Specifically, I’d love to be transported back to being 4, but all my friends would be the 4-year-old version of my present day buddies. It wouldn’t even occur to me to “worry” about girls, and the hormones that make me obsess over them wouldn’t be there, but I could still have an innocent playground kiss with my girl friends (“She’s my girl, and she’s a friend, but she’s not my girlfriend!” to quote my 4-year-old self. 
).
I have to say, though, that 25 is treating me all right, and I wouldn’t mind staying here forever. I’m just old enough to be taken seriously, but not so old that I myself am too serious about anything.
Someone having an issue with their sexuality, or lack thereof?
Don’t forget, when you’re four years old, you won’t ever fall in love, you shouldn’t ever make love, and you can’t even hardly read. So much for appreciating literature or music. Or a good wine for that matter.
You’re probably on to something.
4 is a bit young. If I think about it more I’d pick a later age (but still childhood). As an adult I do appreciate music and other fine things but all the time I know that ANY pleasurable experience wears off over time and the more time we spend appreciating things the quicker they wear off. As a child I was never really aware of the fact that 90 percent of life is mundane and I appreciated the opposite sex, and music, and I had the ability to easily make friends, with whom I would have massive amounts of fun playing neighbourhood games (such as manhunt). One memory that sticks in my mind is listening to Dire Straits (I want my MTV) on the way to Prestatyn in the back of the car. That was the first time I remember appreciating music and I was about 10 at the time.
Plus: When you’re a kid; every single day is about having fun.
I like 25. Cheap car insurance, a bit of experience, not too much adulthood intruding in.
I didn’t have a ‘great’ childhood as I was worried about everything from the age of about two, but if I could go back to be a kid for a while, knowing what I know now, I would probably enjoy it.
Yeah, if life wasn’t a shithole back then.
It’s difficult if you tie it to events in your life. I think optimum would be anywhere in the 25-35 range, but I started my family at 35, so I would think the time with my kids at home is going to be the best of all. So I’d like to be, oh, 27, but have my family…anyway, I haven’t changed very much physically since I was in my late 20s/early 30s (I’m 41 now), so I don’t look back on those years longing for a more spritely form, but more about the feeling that Life was still ahead of me.
I’m 32 as we speak and lovin’ life every day!!
I’ve had several great periods in my life and aim to have many, MANY more!!
Ask me this question again on my deathbed (aged 112!!) what period of my life I wanna go back and be stuck in!
I have to say I’m not at all keen on being 5 again. My childhood was fine. It was just that I have the coolest most reasonable parents but come from a petty small town and as early as I have memories I remember people (adults and kids) seeing me as rude, too sloppy, without the right manners or the right clothes or the generally approved way of being. I was just being the way I was used to at home but still felt they disapproved of and as a young kid I just could not work out why or what I was doing wrong. When I was about 14 I copped on that these people were just narrowminded and that has made such a difference in my life.
Okay, enough whining, there’s worse faiths than having nice parents.
What age would I be? Eighteen or over, I think. I’m now 26 and perfectly happy with it. This thread bears that out, too. Lucky me. Woo hoo!