"Oh you like to think you're a god. Well you're not a god, you're just a parasite here now with jealousy and envy, longing for the lives of others. You feed on them on the memory of love and lose and birth and death and joy and sorrow so. So, come on then, take mine. Take my memories. And I hope you have a big appetite. Because I've lived a long life and I've seen a few things. I walked away from the last great time war. I marked the passing of the time lords. I saw the birth of the universe and watched as time ran out, moment by moment, until nothing remained. No time, no space. Just me!I walked in universes  where the laws of physics were devised by the mind of a mad man. And I've watched universes freeze and creation burn. I've seen things you wouldn't believe! 
I have lost things you will never understand! And I know things, secrets that must never be told, knowledge that must never be spoken. Secrets that will make parasite gods blaze. So come on then! Take it! Take it all, baby! Have it! You have it all!"~The Doctor

Love this quote. It shows The Doctor's true self. He hates himself for what he's done but he carries on to help others. He's seen bad things, terrible things but he's also seen amazing and unimaginable things. He's the best person in the world though he doesn't like to think that of himself. He's cheeky and smart and so much more. He's lived a long life but he soldiers on, he carries on to help others, always putting them before himself. He is the most generous, unselfish, amazing person in the world.

So rant over, but that's true and it is one of my favourite Matt Smith quotes.

Okay, favourite David Tennant quote. That's hard, there's so many good ones but one I never forget is this:

"I'm the Doctor. I'm a Time Lord. I'm from the planet Gallifrey in the constellation Kasterborous. I'm 903 years old, and I am the man whose gonna save all of your lives and all 6 billion people below. You got a problem with that? In that case, allons-y!"