The answer to this question, which may or may not be surprising to you, is women (for several product categories). Despite the blurring of gender roles, this remains true.
“One way of judging would be by who controls the purse strings. As new data from the Statista Global Consumer Survey 2018 shows though, this answer would usually depend on the kind of purchases you’re talking about.”
“When asked in which categories they personally make the purchasing decisions, there were some clear splits between men and women. The largest gap was for daily consumer goods such as food and drink. 81 percent of women said they make the decisions in this area, compared to 65 percent of men – a difference of 16 percentage points. On the other end of the scale, men are apparently more often in the driving seat when it comes to buying a vehicle. In this category, 50 percent of women and 64 percent of men said they made the decision themselves.”
“Note: 30 percent of respondents said they were either single/unmarried or divorced/widowed at the time of survey. The results are therefore not completely representative of relationship dynamics, but rather gender differences generally.”