Anyway, it is a tricky one I will admit that.
If the Fiesta had been a diesel then I would say that, at least its the 1.25 and not the very dated 1.3. I had a 2004 Fiesta 'Zetec' 1.4 on loan back in 2004 and it was a nice little car. Handled well, rode bumps much better than I was expecting and the interior was fairly spacious for a small car. However the engine was a bit crap, seemed heavy on fuel and had little go in it, it was smooth and decent around town though. But on the motorways there was so much tyre noise I was getting a bit annoyed by it. I also hated the interior plastics, very cheap and not at all tactile. Luckily that shape Fiesta seems to have shaken the rusting reputation of the previous version.
Ive never driven a 306 but I believe they are good cars and yours having an XUD should be almost bomb proof. I would certainly bank on that one as being the longer living car. The 306 still looks smart and its the facelift in silver, which is probably the best looking.
Hmm, a Fiesta which you have had from new or a better equipped 306 diesel? 306 and not just because its French