I think Di Maria looks better than Krasic. I saw him play in the Everton game and I've seen bits of him in other games and I've managed him for 10 seasons in football manager
Krasic I don't know, he looks good but Dzagoev looks far better.
Looking on wiki the only thing that would concern me about Di Maria is his lack of goals. Only 4 from 60 appearances Krasic has 24 from 160 appearances which is a much better tally. Dzagoev looks a class player, and he is still only 19. Maybe we should buy them both