Zwave lightbulbs are good zwave repeaters.
Zigbee lightbulbs are more complicated because it depends on the specific brand. For example, the IKEA Tradfri bulbs happen to be good zigbee repeaters on a SmartThings network.
See the FAQ for details:
FAQ: Are Smart Bulbs Repeaters? (Updated Sept 2017: the new answer is yes, but may be inconsistent)