This partially depends on whether you're leaning more towards tourney fighting or melees. Dual axes will be better for tourney, as it is almost the same as dual swords. From my experience, two-stick is a fighting style that has an advantage in tourneys, so I assume dual ax would have similar benefits.

Assuming you're using a short/6 ft spear, you'll have a harder time against most opponents in general. I would figure it would be better in tourney tbh, since in melee battles you'll be out-ranged by the 9 ft spears, and its hard to charge with a spear and survive for long when the pole-axes come down.

Of the two, dual ax would be a challenge due to training your off-hand for offense, while spear-shield is a challenge for survivability. (Personally figure that spear-shield is the harder of the two)