The Libertad has great artwork and it comes in 1/20oz, 1/10oz, 1/4oz, 1/2oz, 1oz, 2oz, 5oz and kilo sizes as well as proofs and annual proof sets. That's hard to argue with. If you're in Canada or the US, the ASE has superior liquidity and gets a better price when you sell. Many LCS's and show vendors here treat and price Libertads like generic rounds because the Libs have no denomination. I buy all the Libs I can find at generic round prices. Shawn was right about those nasty cardboard tubes, too. If you buy a tube of older Libs, the coins are always absolutely grimy.
If you're in Canada/US and you want superior liquidity and a better selling price, ASEs are the way to go. In Australia, I don't know. I'd guess the shipping charges have to make prices on ASEs and Libs nasty. You might get better value for your dollar with Kooks or Koalas.