What car should I choose ford ka or ford focus?

Basically my parents have this ford focus and its coming up to my 17th birthday so they said I could have that car if I put some money towards it which i'm willing to do however a family friend who is a mechanic is selling a Ford ka and he thinks that is a better first car for me. The focus is diesel but I think the ka is petrol. Which one is cheaper, safer or better as a first car?

The Focus

The Focus is a much better car as the Ka (1st gen) are complete rust buckets. You do not need a small car as a first one.

The Focus is a better car, but the insurance will be cheaper for the Ka.

Without any doubt the Focus is far better than the KA, especially in diesel form. I wonder why the friend thinks the KA is better for you? Might it just be that he has something to gain? Your problem is likely to be insurance. Get some quotes as the Focus is not an insurance group one car.