1.8 will benefit you if you dont want to pay out for DPF servicing. Its got a bit more kick than the 1.6, but if finances are something you want to look at, you need to check the tax bracket and make sure that your happy with the amount you have to pay our dear government for using the roads!
you have to think about how much mileage you do and if its worth it firstly.
i have a 1.8 and love it....no dpf to worry about!
21'000 on the clock
get about 51mpg on my average commute
no problems so far with DPF (owned the for just over 16 months)
and I do less than 7000 a year mileage, nice car to drive , I will most likely go for a petrol for my next car though, seen as the petrols have fairly good mpg now.
As Sal says, need to look at your average mileage first. Diesels can be a false economy for a lot of people who assume lower fuel price equals lower cost. But the sale price is higher so you need to be doing X miles to offset this firstly.
And if it's mainly short trips there prob wouldn't be much difference in MPG anyway.
DPF issues have been mentioned, injector troubles are possible, turbo, clutch etc etc.
Wasn't the turbo issue on the 1.6 more of a problem on the early cars , I dont think its much of a problem now?