a milf isn't necessarily an older chick and not all older chicks have kids so when it comes down to it, the one with less baggage (and possible stretch marks due to being preggers).
i don't really like other peoples kids (too bad these kids can't take a hint, go play in the highway), i can barely tolerate my relatives, teen and younger, add the fathers of those kids to the mix, and it's nothin' but potential headaches. besides, if you make a mistake (imo) and settle down, the childless one is easier to break up with, whereas the milf's kids may be hurt and pull on those emotional heartstrings, that every man should deaden, which could change decisions and make it worse for everyone involved.
that being said, hit both and get out before it get's too serious