Lumens (lm) measure light output. A 400 lm LED bulb gives the same light output as a 35W incandescent bulb. But it uses only 6.3W of energy. We have light sources in 100 lm, 200 lm, 400 lm, 600 lm, 1000 lm and 1800 lm.
Think about where you’ll use it. Most LED bulbs are dimmable, RYET are non dimmable and all TRÅDFRI are wirelessly dimmable. For spots you usually use a bulb with beam angle. Bulbs with wider beams give a general light, while bulbs with narrow beams give a directed light. Candle-shaped bulbs direct the light better in, for example, a lamp with a long shade.