So, I decided that the bassoon is what I would pursue next in the woodwind family.

So this is just a hobby then. In which case the quality of the bassoon will be of less importance than "does it actually play much of anything"....which it turns out for a surprising number of bassoons in a price range most people consider reasonable, is "no"

The first thing you need to do is ignore the extraneous information...all the reed stuff? boot strap? That stuff is pennies. That's like choosing one house over another because the seller threw in a free set of towels.

Further, the fact that someone is throwing that stuff in makes me think that the seller is trying to make you overlook important things...like is the instrument actually playable.

The fact that the seller says "it plays fine" is also a bit of a red flag (for me anyway)....what seller is going to say "hey buy my bassoon, it plays like shit!"

The fact that there are no cracks is nice, but in the end not sufficient...i've come across a good many bassoons that meet the "NOT CRACKED!!!" standard, but are not in fact playable.

That all said, given the fact that the plastic bassoon will not age like a wood bassoon, and will likely be playable despite not being maintained, and it was demonstrably serviced, I'd go with that.

The high-d key should be so low on your list of concerns here. Maybe marginally of more importance than the reed stuff....but it doesn't matter for three reasons: 1) as a (presumed?) hobbyist, I highly doubt you'll run across lit where it will be necessary 2) you can play a high D without it 3) you could always add one later if you really needed it

So anyway, I'd go for the fox.