It's obvious.
If you want sex: Younger women are more physically attractive, softer, tighter, and more open to new types of sex (older women have ruled out stuff they don't like).
If you want a relationship: Younger women can have more first-time experiences with you, are less jaded, have less baggage (exes, kids, etc.), have less previous partners to judge you against, and are more likely to properly love you (pair-bonding ability reduces with experience).
If you want a family: Younger women produce healthier kids, and are less likely to initiate divorce.
If you're desperate for anything: Younger women demand less of their partners. Older women expect experience, degrees, careers, wealth, properties. They're also more likely to badger you for marriage.
Foids go stale as they age, and don't even grow smart enough to notice why.