I say The Doctor because he can just sonic Vader's saber and make it malfunction. Sure Vader has the Force, but he is mostly mechanic and The Doctor's sonic screwdriver can pretty much demolish anything mechanical. Besides, The Doctor has faced enemies much worse than Vader *coughDalekscough*.
I voted Vader! Why? He can freaking CHOKE you with his MIND! AND he wields and awesome weapon! Yeah sure he's a dick to his kids in 'ANH' and 'ESB' (and, hell, even in 'ROTJ'...but he redeems himself *sniff* Pssh, I didn't cry when he died. Nope, not at all! <-- totally did cry )
But dude, who wouldn't want THIS playing every time they walk through a door? [link] COOLEST. THEM. EVAH! Not only that but Vader wins just for having the voice of James Earl Jones XD!