bro...i have experiences both...in my opinion slim aluminium core radiator made by denso is better that its big brother which is wider and thicker...
the big radiator takes more time to heat up..and also takes more time to cool down...
the air passes easily in the slim radiator and dissipates heat quickly as compared to thick one...which is better in my opinion.
also more air passes through AC condenser...which is partialy in front of radiator...so some improvement in AC performance...
if your cooling system is okay...then the slim radiator is more than enough to do the job....getting the bigger one is waste of money...
my 1.6 Gti had denso aluminium core radiator from factory...but IMO...best is copper core ...which is expensive and best conductor of heat...