I think it's biased towards the party in the middle.
Australia doesn't have a party in the middle. It has two major parties, so it's not a problem. We have the Conservatives, the Liberals, and the NDP. With alternative voting, if the NDP candidate is discarded and the second choice votes are taken, what are the chances they're going to vote Conservative? I don't think so. When the Conservative votes are discarded, what are the chances they're going to vote NDP?
The CBC did a study of the 2015 election and what the results would have been had we had alternative voting. The Liberals would have had 40 more seats. They would have had 66% of the seats with 39% of the vote. I honestly don't think that you can choose an electoral system that favours one party. It doesn't in Australia, but it would here.