Park hoppers and a car are not necessities......we've done alot of trips to WDw (over 40) and never used a car on any, it's just an added expense....hoppers are the same, you can easily do the same park all day.....
We've never stayed at the POFQ but if we ever stay moderate, that would be the one we would pick, we visit there every trip for one day, but still, if we did, we'd never rent a car and probably do the hoppers there....
Poly has alot of convenience (but at a price) we have stayed at the Poly quite a few times but it was years ago, rates weren't so high and better discounts were out but those stays were always amazing....liked the monorail and big ferry as options...bus travel was always iffy there for us but that was alot of years ago....bigger rooms and you are comparing a moderate to a deluxe so do as you may.....skip the rental and hoppers and stay at the Poly, you won't regret it....