Well 'Helen Queen' the car looks a nice example but then looks can be deceiving , images , write up all seems excellent , BUT do your own checks , make sure the service history details are correct in the service books as per the advert, the price is about right for the age/model/ mileage. You need to personally inspect the car to ensure it is what is being advertised. If you are unsure about any aspect maybe an independent inspection by i.e. AA , RAC for peace of mind.
Used over new - how much money do you have to spend , its as simple as that , if you've got £25K plus buy a new one , if that's what you want.
As for better cars for 10k, it really is a personal choice of what you want the car for ? looks? performance.
All the usual things accident damage, HPI / Experian check to ensure its not stolen, been in a major accident, out standing finance and most important dealer reputation, Google the business you are thinking of dealing with , read their reviews.
Hope this helps you but please feel if I can help further.
Umesh