It's best to list on more than one platform to maximise your chances of a sale.
Make sure you keep track of what's listed where, pricing details and offers received (a spreadsheet works best for this). It's also good practice to remove domains from other platforms once they are sold. This all takes a bit of admin work, but being organised from the start pays off in the long run.
I list .com.au on Netfleet and Sedo. All of my domains (that are for sale) are listed on Sedo. I was also on Afternic (and others) in the past and I'll be looking to add my domains on Afternic again soon.