I prefer the E Max over the Metz by a longshot. It's compound is formulated for longer, "extended" wear and the results for most that have switched over to it confirms that, on average, the B'stone provides 10-20% longer wear.
The Carpenter Racing team, both at their local dragstrip (Atco) where they broke into the 8 second range for the quarter mile and out at the Bonneville Salt Flats where in 2013 Jason DiSalvo set the world land speed record in the heavy cruiser class, did both on Metzelers and they had their pick of the litter for tires.
My own experience on the road jibes with Mittzy's and Rocket Scientists somewhat, except that when I've gotten down to the final 10-15% of useful tread on the E Max it was very noticeably more squirrely, breaking traction more frequently and easily, with or in the absence of braking, than the Metzeler. The same slippery or less grippy trait was keenly prominent or more noticeable with the B'stone when the road surface temps cooled with the seasons here.