Does the brand of LED low beam headlights make a significant difference in the visibility or is Lumens and white (6000-6500) color is what I should focus on when buying Led bulbs. I am wanting an upgrade to stock bulbs.
Thanks.

Quality and dispersion make the biggest difference. There are so many brands out there that it'* hard to differentiate.

Philips has gone to some great effort to make DOT approved bulbs while the others are generally not DOT approved. Maybe that'* a good place to start?

6000+ is where they start turning blue. Personally, I'd stay as low as possible in that range.

I have seen fahren bulbs. My light housing has a round cover at the back. The led bulbs mostly have a fan on them..how is the fan going to cool if it is enclosed and I don't see any vent openings on the housing. Also there is barely any space inside the housing with the cover on..How will there be space for the fan attached to the back of bulb...Am I not to put the cover on??

If you don't put the cover on, dirt and junk will build up inside. If it will fit, it might stay cool enough just cycling air through the heat sink and losing the heat through the walls of the headlight assembly, but no guarantees that it will stay cool enough during hot seasons.

There'* a saying: Install custom parts, have custom problems.

This could be a good example.

I suggest you go with a product that specifically says it fits the car you're installing in. That way you have some idea that the manufacturer expects that it will be installed under that cap etc.

In a few years, they will probably innovate their way to not needing fans and giant heat sinks, but they're not there yet.