Considering that Blood Legion wiped (yes they all died) on the enrage timer and just managed to kill the boss in the same second while Paragon killed the boss 15, yes 15 seconds before enrage with three healers tells me the dps requirements once again is much steeper on 25 man.
I just presented you the facts, now you can go ahead and make asumptions on which mode is harder.
Personally I think that the other 10 man guilds are just that much worse than both the 25 man guilds but ofc also paragon. In the past there were no real good 10 man guild (despite 10 mans being easier). That is also a fact, do you remember noxa? the 25 man guild that came out of nowhere because they picked their 10 best players and destroyed all 10 man guilds but also most 25 man guilds.