main concerns:
1 fuel consumption
TDCI would definitely be the best in FC follow by 1.2 turbo
my polo tsi on full tank (40litres) in city driving around 530km, on highway around 600km (penang to kl at 120kph, uses half tank)

2 maintenance cost
they should be similar, it's the service centre u have to worry about.
naza i have no experience, fords are stuck with sime darby
vw have a number sc of choices in KL/selangor
last year's polo gti batch have piston ring recall issue

3 reliability (on par with vios, city; don't want like proton!!!)
TDCI is good, but a bit dated on interior.
Polo TSI so far i only have minor issues (aircon piping rattling, easy fix)
308t no experience but some forum mention electronics issue (change battery solves it i think)

4 till death do us part-type of owner *not changing car till it's time to write off; my previous car all used >9years
so far vw is offering 5 year unlimited milage warranty for all their range
i'm happy with my polo tsi interior, i'm around 170cm 60kg. so it's ok

polo gti booking is a major pile up all the way to next year it seems,
space wise, tdci & 308t wins. been in my friends TDCI driving to singapore b4, it's comfortable
if u can still manage to get 2011 unreg golf tsi, it has a big chunk of discount (10k+)

new focus probably won't have turbo diesel only petrol (speculations)
320nm torque from TDCI is yummy