Simply due to its proximity to the stage, most fans would prefer seats in section 103. For the Duran Duran concert (and most shows at the Molson Amp), the first row in 103 is just five rows from the stage. However, it is worth noting that high-number seats in 103 have an extreme angle to the stage, while lower-number seats are more head-on.
Section 302 provides a decent view of the stage and is covered by the roof, but the first row is roughly 60 rows from the stage - it simply can't compete from the awesome standpoint of being close. If ticket prices are similar, opt for seats in 103.
Finally, it's worth noting that rows at the Molson Amp are lettered, not numbered. Row 1 may refer to Row A, but you'll want to make sure before making a final purchasing decision.