Carpet: wool rich, polyester or polypropylene?? Feeling overwhelmed

[Acornacorn]

Our loft conversion is nearly complete so we've started to look at carpet. Went to a local carpet dealer and we're now feeling overwhelmed - and shocked how expensive it is (I think we were just naive).
Think we've ruled out having any wool in the carpet because apparently this is an area prone to moths.
I've found a polyester carpet I like that looks a lot like wool and I love the fact it's stain resistant (and nothing like the horrid synthetic carpet I remember as a child). I'm worried it'll flatten and look awful in time, though.

So please tell me your advice when it comes to carpet. I'm feeling a bit lost.

If you want something that will last and look good for years then the 80% wool is the only way to go.wool is naturally resistant to stains if they are treated in time. Avoid Vanish, it bleaches.
On stairs wool is the safest, if you slip man made material can give you friction burns.
Also, Wool carpets can be repaired if damaged. We had a wool carpet on our stairs for 27 years ( plain colour) with family life up and down it. When we sold there was not a single threadbare patch! Well worth every penny of the original cost. If you are worried about moths get it treated, they are everywhere!

Thanks @JT05. I had no idea you could treat wool carpet to prevent moths. How do you do that?

There are sprays on the market for preventing moths. The make I use is Zero. I would ask at the carpet shop about pre treating. Moths and carpet beetle are rife everywhere. I think central heating has a large part to play. Our houses don't get cold enough to kill off the larva. However, although I have had bouts of clothes moths, I have never had carpet moths in any wool carpet.