I am not in your field. I don't know your specific circumstances. However, the answer seems kind of obvious to me.
You go with the funding.
You are deciding between the two premier European universities. King's reputation is barely lesser than that of Oxford. Why would you take 3 years of loans, if King's is giving you a 'prestigious scholarship'? Besides, you will put this full scholarship on your CV - and it will look waaaaay cooler for potential employers than an unfunded degree from Oxford.
Now, of course, if you are independently wealthy (you did mention taking out loans... but one never knows) - of course, it doesn't really matter what to choose. But even then... King's, a fantastic university, is offering you full funding!! This sounds like a dream situation to thousands of computer scientists all over the world, no?
Anyhow, congratulations on the luxury of choice you have and the very best deciding where to go!