Since the time I entered the level 10 arena I've been keeping notes of the people I play against.
I've seen 27 lawtia decks, 39 gowen, 26 falcow and 9 refress. Clearly gowen is on top and refress is criminally underrepresented. Some of those lawtia decks I faced probably came from earlier when it was more popular but it still seems to be a reasonable force now.
As for lawtia vs falcow I think its a fairly even match that really depends on skill, luck, timing and who has the better soul cards.