Although I haven't driven the 1.5 variant, however, power-wise the difference of just 167cc doesn't seem too much. Nevertheless, 1.5 ATIV has more features like digital climate control, push start, chrome handles (inside and outside), a rear camera with a screen and a distinct MID. The price difference is like 2.7 lacs between the top 1.3 variant and top 1.5 variant.
You may consider your daily drive route before taking the purchase decision. For heavy traffic - go for 1.3, for highway travel 1.3 and 1.5 both seems good options. Weight to power ratio of Yaris is better as compared to the variants of Corolla it has replaced.