The Golf Plus is not a competitor. Its a large car based on the Golf, which is a C-Segment family hatch. This Kia is smaller in and out (ignore the wheelbase length), and based on a Hyundia i20, a B-Segment supermini. The two simply don't compare.
There is also the small fact the Golf Plus is considereably technologically advanced and a few years ahead of this Kia, and has much bigger engines (105/140 TDI and 80/ 122 TSI) as well as sophiscated 6-speed manual transmissions and 6/7-speed DSG transmissions.
They do not compare in a single way. This Kia is firmly in the supemini MPV class. Its key rivals are the Jazz, Note, Meriva, Modus, Fusion and perhaps the Mercedes A-Class at a push. If VW came out with a 'Polo Plus' MPV it would no doubt be another rival for this Kia, but the Golf Plus simply is not. The Golf Plus' rivals are 5-seat C-Segment MPVs like the Scenic, C4 Picasso, C-Max, Altea and again at a push the Mercedes B-Class.