I have a vinyl awning and that would be my preference. Cleaning off the bird and fruit bat poo is much easier and it is genuinely waterproof if water happens to pool, unlike canvas where a pool of water can "break through" the proofing. If it's rolled up wet and left (sometimes unavoidable) any mould spots can be washed off with weak bleach.
I have had a vinyl annex for 10yrs & it is still OK.
Issues with vinyl .. Can tear at stress points .. but easily fixed DIY May get 'rust' stains that are very difficult/impossible to remove. The screen printed colour may wear off at rubbing points. Some say that they are hotter but I've not noticed it
Pluses Water proof (as mentioned by others) Can be packed up damp .. but watch out for rust spots Don't smell (except maybe when new) Hang without creases .. although the creases soon come out of canvas Easily cleaned (see previous comment about mold etc)
Having said that a mate in the business 'The Awning Man' highly recommends good quality canvas .. so there you go!
