You know there's one lesson its taken me almost 30 years to learn! I am always narrowing the field down to one player as fast as I can because I prefer to be in a relationship.
Take your time, get to know both girls - you don't have an exclusivity agreement with either yet and then you can chose from there.
I would be inclined to agree that the 20 year old would probably have more in common with you but don't be in a rush - or you may find yourself rushing into a mistake!
I think the mistake a lot of us make is thinking the state-appointed shrink is our friend. - Jack Handy