Generally it's just as Cccactus said 2 slower cards in crossfire are much weaker and not worth than one high end strong gpu like the r9 280x!
But if you are asking i'd rate the r9 280x as no1 gtx 770 as no2 and since you mention them in your post i bet you already have the budget for those so don't bother with the other ones and take one of those 2, they are the strongest in your options.