If you would like a pair I would definiately get Campbells, all my winter whites live on their own except for Stan & Ollie who are still babies. Campbells are much more likely (in my experience) to continue to live harmonously for the duration of their little lives.
Temperament wise I don't think the Campbells are more nippy, they're both nippy but I've never been "hurt" by either - it's usually just a warning which I usually heed lol
Just "meet" as many as you can (in the fur) and decide which is the one for you
Good luck, you won't be dissapointed they are all fabulous