The best lighting for video calls

A webcam sets its exposure for the whole frame. If the brightest thing in the frame is a window or a lamp behind you, it exposes for that, and your face drops into shadow. That is why the same laptop looks fine facing a window and terrible with its back to one.

The fix is light on your face from the front. You can get it by turning your desk to face the window, but a small video light does it every time, day or night, and lets you set the color to match the room. A monitor light bar is a different tool: it lights the desk, not you, and the difference matters when you are choosing.

Elgato Key Light Air MK.2 - the pick. Up to 2,100 lumens from a panel on a desk clamp, adjustable from 2900K to 7000K, with a published CRI above 94. It has enough output to hold its own against a bright window and enough range to match a warm lamp-lit room, and it runs from USB-C, an adapter or a battery bank.
Cons: peak output depends on the power source; no wall adapter in the box; the clamp and panel take desk space.

Logitech Litra Glow - for everyday calls on a small desk. 250 lumens at CRI 93 across 2700K to 6500K, clipped to the top of the monitor and powered by a USB port. Close to your face, a small light goes a long way, and it leaves the desk completely clear.
Cons: 250 lumens will not overpower a sunny window behind you; it needs a USB-A port; no battery.

BenQ ScreenBar Halo - for the desk, not the camera. 800 lux at the center of the desk from 45 cm, CRI 95+ and stepless 2700K to 6500K, from a bar on top of the monitor with auto-dimming. It is the right answer to reading papers beside a screen without glare, and a partner to a face light rather than a substitute.
Cons: rated in lux on the desk, not lumens; it does not light your face; the controller runs on AAA batteries.

Light from the front. Put the light behind or beside the monitor, facing you. If you can, turn the desk so a window is in front of you rather than behind.

Match the room's color. Set the light warm if the room is lit by warm lamps and cooler near a daylight window. A face that is a different color from the wall behind it looks wrong on camera. The scale is in the color temperature guide.

Soften, do not blast. Start low and raise the brightness until your face is clearly lit. A light turned all the way up at arm's length is glare - see glare and visual comfort.

Light the room too. A lit face in a black room looks like an interrogation. A lamp behind you, dimmer than your face light, adds depth - the whole room plan is in home office lighting.