I prefer Zoey and Louis over Zoey and Ellis. There are so many voice lines from L4D1 that show how much Zoey really loves Louis, and they belong together. The Zoey and Ellis ship just doesn't make sense. For one, it violates existing canon, and for another, it's just silly: Ellis is pants on head ♥♥♥♥♥♥♥♥, a few dimes short of a nickel, while Louis is very intelligent, and of course Zoey would choose someone smarter with more dignity.
I do really love the Rochelle and Francis pairing. Francis seems very traditional and a gentlemen, and of course Rochelle would love him treating her like a lady. They're both pretty mature and sensible and perfect for each other.
Thoughts? What characters do you like the canons of? What are your favorite non-canonical ships? Which characters in L4D1 and 2 would you like to see with new pairings in L4D3?