Nasus or Veigar?

Veigar is pretty squishy and likes fighting squishy targets, he's not a great fit for top lane.

Why not both.

If you like stacking and play top, the obvious choice is nasus.

Thresh is a cheesy choice up there too.

For midlane stacking, veigar is the obvious stacker, and bard is the cheesy choice.

In new runes everyone can be a stacker with the right runes though.

Depends if you want a mage or a juggernaut.

Either way, you just need to like Jenga.

big stax

Veigar does not work in top lane. You might think: tanky target, maybe a melee champ, means more stacks! But it only means you have to build mana items early and sacrifice dmg potential, you have no lane pressure to keep enemy jngler from camping bot, you have no map presence to be a threat & since youre building mana you wont have any dmg early to mid game.