If I had to set sail on one ship and one ship only it would be Mavis x Zeref! I love this one so much, it's the perfect ship between light and dark!
Another one I really like is Cobra(Erik) x Kinana! I'm not exactly sure why but I really like this couple, they've been through so much. And he's a real man, going to jail for life by himself so Kinana wouldn't get dragged down with him! As Elfman would say, "That's a Man!!"
Cana x Bacchus are perfect for eachother I think! They will never get mad because their partner is too drunk cause they would both be really drunk! They just seem like they fit together to me.
Last but not least Wendy x Cheria! These two were in my last card bit that's just because I love this pair so much!! I totally ship these two all the way! My 2nd favorite ship behind Mavis x Zeref!