Difficult to fault or add any further value to what BBD says. Very well written.

The Mondeo is turbo but the Mazda is n/a (naturally aspirated). So while their power outputs are not that far apart and the Mazda's 0-62 time is only 0.7 seconds off the Mondeo's, be in no doubt that the Mondeo will feel much more muscular in everyday use. The torque figure comparison explains all with the Mazda offering a relatively modest 193nm at a highish 4500rpm next to the Mondeo's 240nm from 1600-4000rpm. What this means to you is that in order to keep pace with a Mondeo, you will need to be working the engine harder and you will need to change gear more often.

Reliability?, well the Mazda would usually be considered the better bet. Not that the Ford is likely to be unreliable, just not as reliable as the Mazda. That does rather rely on the car having been looked after though, so I'm put off by your use of "reasonable service history". The Mazda is a chain drive, which some folk think of as the holy grail for reliability, but in fact without proper maintenance this can have its own problems. The Mondeo (AFAIK) is belt drive, so you need to ensure that you are not buying a car where this is either overdue or needs doing shortly.

One last point, you have not said whether these are manual or auto. If auto, I'd leave the Mondeo as that Powershift DCT transmission doesn't have a great reputation.

From a handling pov, I doubt if there's much in them as they are both from the time when Ford had a ite-up with Mazda and shared platforms - I'm presuming these two cars did as the Focus m2 and Mazda3 gen-1 did, etc.

Personal preference really as well as certain reliability issues with some sub components either car may or may not have. Still, with older cars, as long as it's not seriously corroding, has a full service history and no bad record of MOT failures (more of a guide to how well previous owners looked after them than anything else), worth a look for not much outlay if ok on inspection by someone with experience. At that age, there will be some consumables to replace every so often - mainly suspension parts and brakes, and if you're unlucky, the odd electrical gremlin or A/C issue.

I personally (as a Mazda fan and long-standing car owner) am less keen on the looks of the 2nd-gen 6 than the 1st or 3rd, but it's no that bad.

The OP should familiarise themselves with the Reviews section for both cars, especially the 'Good' (and Bad) subsections.

Thanks for the detailed advice BBD, and for everyone else that's given me plenty to think about, it just demonstrates how little I know.

It's the petrol manual, as opposed to auto so that sounds like a good thing, I definitely prefer the looks of the Mondeo. Had another look at the ad for it and noticed it's got full service history, also asked the guy some extra questions and all seems good. The car has passed it's last 5 MOT's with no advisories so all in all looking like a good bet.

Last serviced 7k miles ago, had new rear trailing arm bushes, new gear box oil seals and new rear discs and pads all fitted 2021.

I'll keep looking and do a bit more research from the reviews on here that someone mentioned and take it from there.

Fair point mate, one last question which had slipped my mind, but are these chain or belt driven?

I've looked online but can't tell, my old focus belt needed changing at 100k mile or 10 years, given this Mondeos age I guess the belt would need doing if it hasn't been already.