I had a Superb on loan from a dealer for a couple of days a while back and I thought it was a very nice car. However, its a big car and is heavy and I thought the 130PD felt a bit underpowered pulling around something so big. Like the Passat it's based on, it's most definitely a cruiser and there's little reward for trying the throw it around tight back road bends at speed where it pitches and rolls with plenty of understeer. The ride is a little bouncy over rough surfaces but silky on the motorway. If that doesn't bother you, you get a car that will seat 5 adults in comfort with a massive boot, plenty of equipment and a good quality finish.
With the Mondeo you get something that feels far more nimble and light on its feet - you don't feel like you are driving a big car. The suspension is firmer but it's very well damped so it doesn't bounce. All the controls have more feel, with the exeception of the brakes, and you know exactly where the limits are. The 130 TDCi is a great engine, although it will be a couple of mpg off the PD. The torque band is wider which makes it easier to drive day to day as it doesn't have the all-or-nothing power delivery of the PD engine. Its also chain driven so there is no cambelt to change or snap. Fit and finish are very good on the Mk3 and I've not had any reliability issues with the 2 I've had. The 6 speed facelifted versions are best but will be towards the top end of your budget, however you get more kit, a revised interior, different rear lights, new front bumper etc and IMO are worth the extra.
As to which makes the best purchase, it all depends what you want. If you like driving I reckon you'll prefer the feel of the Mondeo, if you're into crusing around in an armchair and need masses of rear legroom then the Superb will probably make more sense. I suggest you try out both of them and take it from there.
