The types of light sources typically used in cabinet and under-cabinet installations are light-emitting diodes (LEDs), halogen lights and fluorescent lights). Each comes in a range of cool and warm colors, and all more efficient than traditional incandescent bulbs.
If you will be in your home for a while, LEDs are hands-down winners. Initial cost will be highest, but the long bulb life (20 years!) and high energy efficiency will pay it back in two or three years. LEDs are dimmable (with LED-compatible dimmer switches), and come in bars, strips and spots.
Less expensive fluorescents are only dimmable with special ballasts, use more energy than LEDs to product the same light, and may take a few minutes to reach full brightness when turned on.
Halogen bulbs, the least efficient of the three, are often used for high-intensity spotlights, burn hot, are fully dimmable and have no warm-up delay.