Honestly why do you have to choose to kill Paarthurnax and be hated by the Graybeards or not kill him and be hated by the Blades? As far as I'm aware the blades are there to serve the Dragonborn so shouldn't the Dragonborn have finale say in the matter? due to being on console I can't mod the quest but was always currious as to why we couldn't tell delphine to cool her dragon killing jets for this one here at least. I like both sides this quest always annoys me.
On a side note this is my first post on this forum so please go easy on me

thanks
First post, huh? Welcome to the forums,http://www.imperial-library.info/sites/default/files/dogate_til_fishystick.jpg.
As for Paarthurnax, kill him or not, that's your choice, but IMO, you won't be missing out on too terribly much by letting him live. If having the Blades hate you is all that happens, your in fine shape, they (mostly Delphine) have betrayed everything they're sworn to protect (meaning me) unconditionally. The Blades of today are better left as dead. Let Paarthurnax live, at least the beards don't place conditions on you on whether or not they'll help you.