I use Liquid laundry Detergent myself but both powder and liquid laundry detergent will get the clothes just as clean.
The reason I prefer Liquid laundry detergent is the liquid laundry detergent doesn't leave any residue on the clothes and dissolves much better in the water.
But both Liquid and Powder laundry detergent work both the same except for the residue and dissolving issues.