I track my net worth. Income affects that. Expenses affect that. (Asset value changes affect that - I do track investment value changes and dividends quarterly, but personally do not bother updating real estate values from their original appraised value. In my area, real estate values are relatively slow to change.)
Recently, I was curious about savings rate, so I made a spreadsheet each for gross and net. The number for net is about 10% higher. I don't really want to track the deductions from paychecks because both my wife and I get paid weekly, and the numbers often change by a few cents up and down each week. In the future, I'll just use net for calculations. But in the end, when I'm thinking about financial independence, I'm trying to find a point at which (expenses - passive income) + (remaining debts) <= (invested assets). So in addition to tracking net worth, I track invested assets.