Which kind of frame (steel frames or concrete frames) has more strength and stiffness degradation under seismic loads?

Steel frames included with Additional stiffeners at their web will increase their load/Impact intake capacity.

Irrespective of codal provisions, just because of mechanical properties (stress-strain curve) steel structures shall have better response under seismic load condition than RCC structure. Moreover, braced system (damage to non-structural elements) will give better result than moment frame system (more inter-story drift).