Jonas brothers......is what Jonas makes me think of. I prefer Jonathan. I love 'th' names. Also, although both names are from the bible, Jonathan sounds less aggressively religious, more easygoing - to my ears, anyway.
Hmm I am not that keen on either of these. Jonas is too surnamey for me (I know someone whose surname is Jonas) but Jonathan I just find a little dull. I prefer Jonah.