As couriers go, Sendle is as good as most.  They are fairly new and so far are getting good reviews.

However, if you are going to use them make sure you mention it in your listings as there are a lot of buyers who will not buy from you as courier delivery is not convenient for them.

Couriers also do not deliver everywhere despite what they will tell you.  The coverage with Australia Post is far superior to any courier company that I know of.