I think that while "being drafted" isn't a tiebreaker, contract status has to play a part. If Romo wins the job, he's a free agent after this year. If Borregales wins the job, he's got at least 4 years left on his deal for very cheap money. Granted, Romo would be an RFA so they kind of still own his rights for next year, for all intents and purposes, and he'd still be cheap, but ultimately it is still 2 years vs 4 years.
They're both pretty young (Romo 25, Borregales 22) so I don't think age really factors in.