Well, sorry if this is a lame answer but until we know more about their personality we're just going to match them up based on ability and gut instinct.
Of course Blackbeard would fight Luffy.
Van Augur would have to go with Usopp, or have some sort of fight with Usopp so we can see who the better marksman is.
I actually think Shiliew would be great for Zoro. He's just so frightening and insanely strong I think it would be someone that's actually a challenge for him.
Even though Laffitte is said to be the navigator, I think he would make for a great fight with Sanji. This is solely based on the fact that I think their personalities would really clash.
This is kind of hard! It's hard to say because when they actually fight I really doubt it's going to be just the Strawhats against them. If they fought right now, of course the Strawhats would lose though. That's the good part though, they have a long way to go before they face one of the final enemies.