60W lamp is brighter.
Suposing both lamps are designed to operate with the same voltage, as 220V:
The resistance of the 60W lamp is:
The resistance of the 250W lamp is:
If we connect both in series at a 220V mains, the current will be:
As far as Power =
The power dissipated by the 60W lamp is:
And the power dissipated by the 250W lamp is:
So, the 60W lamp will be brighter.