I strongly prefer 100% cotton sheets. I like percale style, which feel crisper. They are kind of like grandma’s old fashioned sheets. The other option for cotton sheets is sateen finish, which are smoother. For me they are unpleasantly clingy.
I see you are in Canada. If it get’s very cold there, you could consider cotton flannel sheets in the winter. They are super cozy.
I don’t pay much attention to thread count as long as they are 100% cotton and percale.
Hard to recommend suppliers, since I’m not in Canada, but...
Amazon has two options that I like:
Economical: Pinzon percale sheets
Splurge: Peru Pima percale sheets
White is a good idea because you can mix and match and bleach, if necessary.