The newer model Scenic (2003>) is a disaster waiting to happen with too much electronics and the awful electric handbrake (even a sticking cable will give you a £600 bill) Diesels are even worse than petrols with lots of EGR, Head and turbo problems (the turbo is almost completely inaccessible too)
Kia, Hyundai and their ilk are nice and cheap, both new and used (depreciation is AWFUL) But parts are ridiculously expensive and sometimes hard to get, even from dealers. Generally they run last generation Japanese technology so are simple enough but this often puts them in a very high tax bracket.
The Focus C-Max is a good car, probably the best in class, but you will pay a premium for one cos everyone knows this. My only complaint is not a big enough boot.
The Zafira is a good enough tool but as you say, a little on the large side and a bit agricultural compared with more modern offerings. Likewise the Galaxy/Alhambra/Sharan. And all of these have NO boot space with all 7 seats in use.
Corrolla Verso, is a good choice, bland and boring but oh so reliable. And surprisingly rare! Buy one if you can find one!
And so to the (Xsara) Picasso. Generally speaking, I hate French cars, but I find myself a reluctant champion of this one. It's not the quickest, or the best handling, or the most economical - and probably not the most reliable. But it does all this pretty well. Because it only has 5 seats, the boot is generous, seats are extremely comfortable and the ride is excellent in the slightly roly poly French tradition. Simply made on very un-Citroen like conservative lines, there is not much to go wrong and not much does. And if it DOES go wrong, bits are cheap as chips and readily available. I paid £3k for the wife's 56 plate 2.0 petrol VTX auto in 2012 with 50k on the clock and a FSH. 4+ years later, it has had only routine servicing and has been utterly reliable. I had to have a 2.0 petrol as that is the only one that comes with an autobox which SWMBO must have and the penalty is £287/yr road tax and a 28mpg thirst (according to the trip computer, but is does do a lot of very short trips) it's pretty quick though with effortless kickdown acceleration and has all the toys you could wish for. Certainly the 1.6 is a bit gutless compared with mine, but the son in law has a 1.8 like Dave's old one, a 55 plate 1.8 petrol manual with a high spec interior and 105k showing which cost him a mere £650 last year. This seems like a happy medium to me, It's cheaper to tax than mine and somewhat better on fuel too. Your £2.5k budget will get you a late, low mileage one of these too!
So for sheer value for money, easy maintainence and a great ride, I have to recommend the Xsara Picasso.
Steve