Will lightning strike a tall tree or a small metal fence that is near the tree? Why?

In general, the factors that affect the location where a lightning bolt will strike includes the height of the object, a pointy shape, and isolation. Presence of a small metal object in the vicinity may not make any difference to where the lightning will strike. Tall trees are more likely to be struck by lightning as compared to a smaller metal fence nearby.
Kindly note that lightning does not make a decision on what to hit, and the details of Earth's surface like fences, poles, etc. are nearly invisible to it until it almost reaches the surface of the Earth. However, taller structures have a higher probability of getting hit by the lightning because they significantly reduce the insulating air gap between the clouds and the ground.