how to choose led light bulbs?

First depends on what will be the application for led light bulbs.

If you are a distributor, want to buy the led light bulbs for distribution, you can choose some with competitive price.

If the led light bulbs are used for projects, need to use the good quality one.

So you need know below factors:

1. what kind of housing the led light bulbs? aluminium will be much better than the plastic type. As the led need to dissipate the heat by the housing. Aluminium is good for heat dissipation.
2. what kind of the driver used inside? the isolated one or the non isolated one?
3. what kind of the led inside?

Then you can take some samples to test.