The latest Leopards are also great. I think Australia still has/had Leopard I tanks? Germany, Sweden and the Netherlands have been cruising around in Leopard IIs for quite a while, and I think they were even improved and upgraded along the way.
However, it's funny we are discussing tanks here, when the topic subject are the most lethal opponents for tanks. Don't you think tanks are getting outdated, and any army having/buying large amounts of tanks is still thinking in terms of the cold war era situations and battlefields? It may be better to invest on mobile forces, fleet of tactical helicopters and attack helicopters to escort them and clear the battlefield of any opponent's tanks, if the air force hasn't already taken care of them!