Ok, this is from my personal experience, Spirit Vikings is horrible, at least for me, I went there for a whole 2x event with a lvl 129 DS using Demon Cry. Now I went to Lycanthopes, I believe is what they're called? :o The white werewolves in El Nath, but I got about a set every 30-45 minutes on 2x with my DS using Demon Cry :o so up to you, but I also had a Kanna at both places.
wolf spiders don't drop them? haha so thats why i didn't get any after staying there for like 2 hours
and yeah spirit vikings drop rate is really really low and I have had no luck with mushmom
haven't tried lycanthropes yet