I don't mind paying a monthly fee for all of them if need be.
I haven't been to WOW in over 5 years but it's cartoon art style and relative simplicity and lots of nonquest things to do seemed like my first choice. I briefly tried Runescape and personally didn't enjoy it.
Previous MMO I played was Tera, beautiful clothes (some of the outfits were GORGEOUS!) but absolutely not kid appropriate (especially the community).