The best LED puck lights

A puck light is a small round fixture that throws a cone of light straight down. That geometry is the whole story: it produces a defined pool with a soft edge, and then nothing.

Which makes it excellent at one job and poor at another. Lighting a specific object - a display case, a curio cabinet, a bookshelf, a single chopping spot - is exactly what a pool of light is for. Lighting eight feet of continuous kitchen counter is not, because you get four bright circles and three dark bands.

Nearly all disappointment in this category is buying pucks for the second job. The format comparison is in strip vs puck vs bar, and the short version is: continuous run means a bar or strip; specific objects mean pucks.

Armacost PureVue puck - the pick. About 375 lumens from 4 watts, which is more than double the budget kits and clears the usual residential efficiency benchmark comfortably. It is designed as part of a proper low-voltage system rather than as a sealed kit, which means it can be planned into a run rather than bought as a fixed set.
Cons: it needs a separate driver, which is a second purchase and something to hide; no Kelvin or CRI published on the product page; and it takes more installation planning than a plug-and-play kit.

LAMPAOUS dimmable puck kit - for a display case. 160 lumens per puck with a rotary dimmer that genuinely runs 0 to 100 percent - most puck kits have fixed output, and a display case at full brightness at night is a bright spot in a dark room. It can be surface mounted or recessed into a 2.5 inch cutout.
Cons: 6000K is very cool, which suits a display case and looks clinical in a kitchen; high CRI is claimed but no figure is published; and 160 lm per puck means a lot of them for any real run.

Enbrighten 18 in. bar - what to buy instead, for a counter. 1,245 lumens at CRI 92 with five color temperature settings, dimming built in, and no extra hardware. Included deliberately: for a continuous counter run this beats any puck arrangement on evenness, output and color quality.
Cons: it is a bar, so it will not fit where a small round fixture would.

WOBANE COB strip - the continuous alternative. CRI 90+ at 3000K in a continuous emitting line with no visible dots, which is the other way to solve the evenness problem.
Cons: no published lumen figure, and a strip cannot be aimed at a single object the way a puck can.

Surface mount if you rent. Recessing a puck means cutting a hole - commonly 2.5 inches - in a cabinet, which is a permanent modification to something that may not be yours. Surface mounting looks slightly less tidy and undoes completely. The adhesive techniques are in under-cabinet lighting that installs without tools.

Set them back from the front edge. A puck mounted at the front of a cabinet underside puts a bright source directly in your eyeline as you stand at the counter. Mounted toward the back, the cabinet lip shields the emitter and you see the lit counter instead of the fixture - see glare and visual comfort.

Overlap the pools. Adjacent pools should overlap slightly at the counter surface, not merely touch. Pools that just meet leave a visible dark seam, which is the specific thing that makes puck runs look patchy.

Mind the heat in a closed cabinet. A recessed puck inside a sealed display case has nowhere to send its heat, and LEDs fail from heat rather than from use. Low-wattage pucks are fine; a run of them inside a closed glass cabinet deserves some ventilation.

For a run along the base of cabinets rather than under the wall units, see toe-kick and cove lighting.