Here's my run down:
The type of fuel and engine size should be based on your use of the car. Here's what I've had and how they were best suited.
Vauxhall Corsa C 1.4 petrol:
Great little car for jetting about in the town centre. Returned decent MPG for town/city driving but not great on the motorway as the little 1.4 really struggles around the 70 mark. a 1.2 would even more so, etc etc. Nice to drive though, but when coming onto a dual carriageway etc, you really could feel the limitation of the engine with slow acceleration.
Toyota Yaris 1.0 petrol:
Ideal for purely town/city. No power whatsoever on motorway. Small engine size delivers lovely MPG though on city roads.
Vauxhall Astra J 1.4 petrol:
Utterly bloody useless. This car should NEVER have been made. The same engine that the Corsa C used, was put into the astra J. To get the car past 40 on the motorway, you need to stick in third. To get from 40-70 takes about 20 seconds in fourth gear. Horrid, horrid car. Even in city driving, this car is awful. See a gap in a the roundabout? Too bad, you'll need a 10 second pause in traffic to pull out in this thing. My drive that's 50 miles (mostly motorway) would use nearly £12 of fuel; since every time you brake on the motorway, you had to ram it into a low gear to get ANY speed back - which aint good for the gearbox either.
Vauxhall Astra J 1.7 Diesel:
Totally different car from the 1.4 petrol. Pulls alright, decent mpg (not great though as the astra is HEAVY car). Worlds apart from the rubbish 1.4 petrol. By no means rapid, but decent.
Ford Fiesta 1.5 Diesel:
Nice little car, pulls well and has the oomf when you push the revs high enough. Gets good motorway mpg and is ok to drive in the city. Again, being a bog standard diesel engine size, it's not mega fast, but has the power to move when you need it.
Seat Leon FR+ 2.0 Diesel:
Only had this car for a day before a transit rear ended it, but this thing was rapid. Incredible pulling power from still even in high gears. Turbo kicks in nice and early so you're rapid from the get go. Easily overtakes and picks up speed even at 70+ in sixth gear. Absolutely loved it. My dads 2.5 petrol Mazda 6 struggled to keep pace with it; which in itself is a rapid car.
Ultimately it comes down to, what car is the engine in and what sort of driving is it going to be doing?
Town/city = small petrol
Town/city with some motorway = mid size petrol 1.6-1.8
Mixture of all and if you want power and aren't a fan of diesels = 1.8+ petrol
Mainly motorway with VERY good mpg = mid diesel
Mainly motorway with better than petrol MPG and very fast = large diesel
I wouldn't recommend town/city driving on a diesel as you need to give diesels a good blast at high speed to clear out the filters etc or you'll run into some costly trouble.