I'd say either 18-21 or 30, depending on your personality. Some folks seem to have their spouse already picked at 18, otherwise... I'd just wait until very late 20's or early 30's unless starting a family early is a priority. I prefer around my own age, give or take a couple years.
Personality is more important than age, with some sanity applied.
This in spades. I have friends who have been together since high school, got married right after college, and are doing very well. Personally, I didn't get married until after college, Army, law school, and a few years in practice. I can't imagine my life working as well any other way. No way I would have wanted to be married while I was in college or in the Army...I was having too much fun being a big kid. Law school was too time demanding for marriage to have worked for me, and again I was having too much fun. Early career was time intensive, and I was still having fun. God knows there were a few women along the way who had me pegged as husband material, even though I was perfectly clear that it was not an option for me at that point. The last I feel lucky to have avoided. When it ended, she started yelling about the fact that she had bought a dress, veil, and put down a deposit on a reception hall. Note that the word marriage never came out of my mouth, and I had never even priced rings, much less bought one.