Why are most people on the top of the Diablo 2 ladder Paladin?

Solution 1:

The reason Paladins dominate the top of ladders is because of the extremely popular Hammerdin build (attacking with Magic Hammers).

With this build, it is very hard to be killed due to the lack of immunities against magic damage in the game (very few monsters are immune), the concentration aura which has a high % of making a hit not interrupt you, as well as the high resistance that comes with the Paladin items typically in this build (Shako, Spirit or HoZ, Hoto, etc.).

Compound this with achieving the highest FCR breakpoint, an Enigma (to teleport), max block (via Holy Shield & Stats), and a mercenary with Holy Freeze, and you have a very good PVM (and to a lesser extent PVP) character.

Since it's essentially the #1 PVM build, people like to use Hammerdins to bot their way to 99, as he is a good candidate for mass Chaos runs as well as Baal runs (although for Baal runs, the Hammerdin must rely on either their mercenary to kill the second Wave or must invest a few points into Holy Bolt as that wave is magic immune).