Apparently it's between DENSO and NGK spark plugs for this engine.
DENSO website looks to be much more helpful when nailing down plugs for a particular car and engine.
From the reviews online, NGK platinum plugs seem to be longer lasting. I think I'll be given them a try.
The shop at the Ukay Centre in westlands has them between 1200-1500 KSHS each (compared to about 205 for the standard ones). Oops.. pocket pinch.