For me, if I'm limited to one, the choice is PE.
First, the cost to benefit ratio is higher (IMHO) with PE than with resin and is generally the cheaper of the two options. Second, PE can frequently correct more problems with a kit than a resin set can fix - most notably, over-scale components, but also missing details. Finally, with PE you generally know you're going to have a "known quality" of parts (usually high) while resin sets can vary from the "very good" to the "terrible".
Now for the reality...
I frequently use both PE and resin on builds. They both have valid purposes and applications. I personally wouldn't want to be limited to just one choice.