It very much depends upon your usage, age of vehicle you're looking at and where it's from in the country - it's not just about engines (if you only do short journeys, then petrol is worth of consideration too).
Scotland - too much salt on the roads for a car with so much aluminium
Towbar - suspension bushes taken a hammering? also check it hasn't been dunked in the sea...
EU5 + DPF vs. EU6?
Specification level - Vogue, Vogue SE or AB? some of the extras come with their own potential issues.
ARC - pipework corrodes and isn't a cheap fix (even if you're doing it 'parts only' expect ~£600 for the pipes, reservoir, isolation bobbins & fluid)
Neither Diesel engine is issue free, the 4.4 has chain issues, the 3.0 has crank issues...