In addition to Yarnsub, you can look up the pattern on Ravelry. Click on ‘yarn ideas’ or ‘projects’ to see what other people have used to make this pattern.
This has the advantage that you can see what the pattern looks like made up in the different yarns, and read the crafters’ notes – some of which can be extremely helpful in making your choice.
Ultimately, the yarn you use will have an impact on the finished product. Cotton will make a heavy blanket, and may ‘grow’ when it’s washed. Acrylic can be soft and easy-care, but can look threadbare and thin after a few washes. Non-superwash wools can felt! You’ll need to swatch and launder to ensure you get the same gauge as the pattern and the feel you want – sometimes more than once.