Zeiss is running a $50 mail in rebate which is attractive.
I don't really liking the ballistic program on the Zeiss. If you are just using the line of site feature them not really a big deal. The multi-position eye cup is a nice feature.
Neither the Leica or the Zeiss have a built in tripod attachment point which would be something nice to have if ranging out pretty far.
I like that the Leica 1600-b gives hold over values (out to 880 yards) in mil or moa increments.
Honestly it's a toss up. I went with the Leica personally because of the overall size of the unit.