It’s usually cheaper. Ordinary distilled white vinegar with 5% acidity is cheap and works great. If you can find a higher acidity even up to 20%, it is going to work faster, but the end results will be the same so don't stress if you can't find it.
You only need a few drops of dishwashing liquid so the brand doesn’t matter. The purpose of the soap is to break the surface tension of the vinegar so it sticks to the weeds, forcing them to absorb it more readily.