There is no universal answer to this question, as which is a more important factor in a buying decision varies depending on: price; type of user; perceived quality; and type of purchase.
In general price matters more for lower valued items and discount matters more for higher valued items
Based on A/B testing and discussions with other professionals, in general women tend to be more interested in the discount, and men more interested in the absolute price. It’s why women’s clothing stores tend to always have items on discount, and where the discount is the most visible marker. Of course there are other factors that come into play, this is just one of them.
Another is the wealth of the user. Typically poorer people will focus on the absolute price more than the discount, as their shopping is more utilitarian in nature. E.g. in the Netherlands if you want to buy beer, there is the Euroshopper beer which is about €0.30 for 450ml on one end of the scale, and craft Belgian beers at about €3.00 each sold next to each other. As people in the Netherlands have more disposable income, and are less price sensitive, they tend to buy towards the middle of the beer price scale. Whereas in places like South Africa, the price difference between common beers in a supermarket is far less and people tend to buy whatever is cheapest.
If the item is perceived as having a high quality, and something that is likely to only be bought once or a few times in a lifetime, the discount tends to matter more. You can often see this logic with men buying tools, or sound systems. I’m sure a similar thing would apply to women and high end handbags or shoes, but I thankfully have no experience with this.
With impulse buys, the discount tends to be more important, as it’s what’s used as justification for the purchase. This also applies to pressure situations where people don’t want to lose out on an “opportunity”. It’s a common negotiating tactic to give a good discount, but limit it in time to create pressure. You’ll often see car salesmen do this sort of thing.
Whereas a purchase where someone takes the time to research it and make their decision carefully, the final price is more significant.
So overall, you’d have to make an informed decision based on what you know about your audience and product. I would strongly suggest A/B testing to be sure, and if possible combined with some sort of user demographics.