I haven't read through this topic on purpose so I don't feel like my answer is influenced by somebody else's sparkling contribution, which is so easily done in politics.
AV all the way for me. I'll keep my reason really simple. With AV you can give your vote much more depth, you're not just voting for your favourite, you have the opportunity to vote for your favourite and technically vote against your least favourite/less liked parties. It's much better that way, because an opinion can NEVER be fully expressed just stating what you like, it has to be opposed by dislikes too in order to give it a more solid construction. That's just my way of seeing things anyways, in a very quick nutshell.