Which logic family would use for a small battery powered circuit CMOS or TTLand why?

For a small battery-powered circuit, CMOS (Complementary Metal-Oxide-Semiconductor) is typically the preferred choice over TTL (Transistor-Transistor Logic). This is because CMOS technology offers significantly lower power consumption, especially in idle states, which extends battery life. Additionally, CMOS circuits have a higher noise margin and can operate at a wider range of supply voltages, making them more versatile for portable applications.