I would only consider the German SUVs if you plan to keep it during the factory warranty period, or getting an extended warranty (which will cost $3k+). Even though you are good with a wrench, if they do end up with issues, they tend to be expensive. The depreciation on those Euro SUVs are also horrendous, even though the first owner took the biggest hit.
Since it sounds like you want more room than the compact SUVs, I'd check out the Honda Pilot, Toyota Highlander, Nissan Pathfinder and/or Murano, and Ford Explorer and/or Edge.
That's my worry. Extended warrenty may be an option by $3k is a ton. I have researched their problems a lot today and it seems like the GLK's have been pretty good machines but who knows.
Speaking on depreciation, they(2013 GLK350) were new at 40K+ and now they are 20kish I cant imagine them being on worse than ford and chevy from here on out. I would never buy a new car for this exact reason.