I first must say I don't like using pucks for UC lighting unless I have no other options. With some cabinets where a skin is covering the bottom I am forced to use them. The puck that I found has the best spread of light is the WAC HR-86 which also is a Xenon bulb. It really does make a difference. Some brands have a very narrow spread and cause a very spotty appearence on the counter. With the WAC's they can be about 18" apart to get fairly even and good illumination.
Paul