14 and 16…and remember, Canon Law is written for the UNIVERSAL Church…not just the Church of the modern, western world, which generally means living in developed, first world areas.
Personally, if a 14 and 16 year old couple came to me and wanted to get married, I’d tell them to wait until they were at least 18 and 20, respectively. At a minimum, I’d need parental permission, or a darn good reason why such should not be sought. In fact, on the marriage intake forms in our diocese, and I assume others as well, there is a line that says, “If you are under 21, do your parents approve of this marriage?”
In the United States, where I assume most of us are from, yes, 14 and 16 are too young. In parts of Asia, Africa, or Latin America, perhaps not necessarily.