Salamanders. Then Raven Guard. Then Iron Hands and in fourth place (but still rather close) Imperial Fists. White Scars? errr... they'll come eventually (in my list).
I think all 1st founding chapters have their place and also think they should add them all before they add any successors.
It's hard for me to pick a favorite non Space Wolves Founding Chapter since I like quite a few of them. To me they all have little things that make them interesting and generally are very fun but I think I'd have to go with Iron Fists out of the options (even though I'm not a fan of their yellow armor, lol.)
