I see 5 things to aim for.
Product quality. Quality matters, as the weak point in any screw-in LED lightbulb replacement is the power supply. The house label cheapies use cheap capacitors and are bound to fail a lot sooner. The internal LEDs proper will outlive us all.
Aiming. Up until LED, all lights made a sphere of light. But if you look at any lighting application, you don't want a sphere - you want a cone or wedge. LEDs natively do make a cone of light of about 160 degrees. In the past we tried to salvage some of the wasted light with reflectors, but those aren't very efficient. Optical lenses are very efficient, and work well with a 160 degree input. So for instance in a 60 degree downlight, almost all the LED's lumens can be brought to bear, where you were lucky to get 1/3 of the incandescent's lumens.
Some LED screw-in lightbulb replacements are built to emit a sphere of light. This is wasteful in most cases.
Lumens per watt. A lumen measures how much light the bulb puts out, in a 360 degree sphere. Incandescents do get credit for the lumens they waste in the wrong direction. This means an LED which emits a cone of light, will be more intense in its active direction than one which emits a sphere of light. So for instance a built-in LED downlight fixture of 1000lm will be much brighter than an incandescent downlight fixture that takes a common Edison bulb of 1000lm.
Lumens per watt is the light efficiency. It is adjusted for how humans see light. but it should be multiplied by the aiming factor.
Color Temperature. This is how blue or yellow the light is. If you've driven at night in the past few years, you notice some headlights are much bluer than most. LEDs can be any color temperature, except they are more efficient at the bluer lights.
- 2700k is a hearth or gaslight color
- 3000k is a halogen color (barely different)
- 3500k is some yellower (greener) fluorescent lights
- 4000k is the standard for fluorescent lights
- 5100k is "daylight" and typical of a cloudy day.
- 6000k is blue-sky daylight.
Color Rendering Index or CRI.
This is a totally different factor than color temperature. This represents how balanced the light appears to the human eye - how natural looking, and is a score from 0 to 100. If you remember old fluorescent lights which made things look really "blah", that is bad CRI. Remember those yellow streetlights (high pressure sodium)? Those have a 20 CRI. The older deep yellow streetlights (low pressure sodium), their CRI went into negative numbers! The early LEDs that looked jarring had a CRI problem.
In an effort to ban fluorescent lights, the government now requires they have very good CRI. The industry responded by making them even better CRI - as high as 98. I pay abut $1.60 a tube for 90 CRI fluorescents, and they look really good. 80 CRI LEDs are readily available and 90 CRI can be had. Incandescents were 99 CRI, being very similar to an ideal.