While I can't comment on the wagon since I never owned one, I'm pretty happy with the ML. Yes, the 98-00 years were considered problematic, but most (at least for me) were corrected under warranty while having other routine services performed. In other words, I've had little to no on-road issues with the SUV.

I prefer the ride height offered with the ML when taking long trips. I don't tow anything yet (so I opted for the 320 instead of the 430 for fuel savings) but it's nice to have when I eventually will.

I'm always hauling something on weekends, so the SUV suits me well. I'm the equipment manager for my daughter's soccer team, as well as a musician, so if I'm not hauling corner flags and soccer balls, I've got amps, speakers and flight cases. Otherwise, it's bags of mulch and flats of perennials on other occasions.

To me, the cargo height advantage is what steered me towards an SUV over a wagon. And for most of my hauling needs, this is essential.

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car