Reply in hope you haven't gone to Ford!
the V50 is a sound choice (but I would say that!). Try to get an SE model with less than 100k on the clock. Check all the electrical equipment. I mean literally push every button and turn every knob.
Engine wise - 2.0l diesels everywhere but not sure on the DPF issues (have a look
here for more info on diesel vs petrol).
As you can see its all about travelling distance. You don't want a D5 to nip to the shops, but would be perfect for long motorway blasts.
Personally I'v owned a 1.8 petrol which was a little gutless on power but did me fine with no major issues and was easy to work on, plus 33mpg on a semi-rural 20 mile commute.
I recon a 1.8 petrol V50 SE with les than 100K shouldn't cost more than say £4000 for a good specimen.
But if you're after seat of your pant power then T5's the way to go :-)