Neither vehicle makes sense as a daily commuter, especially driving 40 miles daily. The newest W126 is 30 years old. There's also a saying that friends don't let friends buy German.
The Hummer is slow, loud, not the most reliable, and expensive to fix if you don't know how to work on it yourself. To be honest though I wouldn't mind picking up a Hunmer myself, but I only have a 4 mile drive to work.
For a daily commuter driving 40+ miles and your budget look for a Civic or a Camry or something along those lines. You don't need a "great" car. You need a decent one you can depend on and that gets good fuel mileage.