K10 - No Ecu faults, no throttle body soldering, no dodgey nats, Retro look + not often you see a modified one on the roads
K11 - Some really nice ones out there, tuning potential
K12 - Underestimated, comfy, all mod cons, frog.
Whatever of the above you have, your going to get attached to it, and everybody sees different things in a car. Some want performance, some want relibility, economy, comfort, safety etc, i mean if the car didn't have what you wanted, why would you buy it? The K11 will win due to popularity