I use sisal - because I find it makes strong rope, I had a ready source of it (since then , dried up!) at a fair price, and most of all .... I still have two whole bales of it!
I love the smell and find sisal OK to work with - if not as good as some other fibres - and off cuts make great tinder.
I have worked a lot with Jute but find it expensive (in comparison) and it does not smell of days spent romping in the summer hay barns of my youth.....
Cotton is frankly boring to work ...