The Pyro must now be the only class where its tertiary(melee) weapon is better than its primary and secondary weapons http://www.steampowered.com/status/tf2/tf2_stats.php Fireaxe does more damage, more crits, and now has the larger "average range" To quote the heavy "oh it is sad day"
The wrench of the engie seems to give a lot of crits, and I can tell you that's true. It does deliver more crits compared to other melees. The second place imo goes to the heavy uppercut, awesome for hitting scouts.