I really don't understand why people are debating about 10/25 mans. There are some fights that are harder as 25 man and some fights that are harder as 10 man. Some are telling that it's harder to get 25 very talented players together, yes it's maybe harder but it doesn't take credit off from 10 man guilds. Now that I have said these things I can say that Paragon was the best 25-man guild in Cataclysm and half from Wotlk and yes I remember kin raiders took world first from DS but still overall Paragon was the best guild in Cataclysm. Now when they are 10-man. There isn't any guild that can challenge them on these world first kills.
Ps: Don't rage too much for the fact