What is best laptop brand and why?

Really depends on what spec/use you are looking for.

Everyone has personal favorites, just like Cars.

IBM Thinkpads used to be the best by a fairly wide margin. But since they sold out to Lenovo, then have dropped back into the pack.

HP has been the #1 selling brand worldwide for the last 4 years.

I would judge best BRAND based on support and quality control since specs are pretty much the same across the board.

You can buy HP laptop...
Moreover quality and product of this company is faithful.