Best Petrol Engine - Reliability - Fabia 2009-14

My daughter used to have a 2001 Fabia Estate SDI - which was great.
After a gap - she has decided to get another Fabia Estate - but as it will be used a fair bit for commuting/shopping in an urban area, she intends to do the responsible thing - and buy a Petrol engined car.
Her budget is about £5K to £6K - which I reckon will get her a 2009 to 2014 car - depending on mileage.
She wants my help - but I don't know much about the VAG Petrol engines for that age range.
It needs to be economical to run and insure - but most of all - it needs to be very reliable.
She isn't a "speed freak" - so we are already ruling out any VR/GT type models - but at times she may need to use it well loaded-up - so also don't want anything under-powered. 
Can you experts tell me which engine(s) to look for - or at least are their any to avoid ??? 
Also are we best looking for the lowest mileage even if it puts it at the older end of that age range - or go for the newest we can find, as long as the mileage isn't astronomical.

Are there any other reliability issues to consider when buying?
Any help much appreciated - THANKS