I enjoy my W124 the most because I can service more stuff on it...and its fun to drive. Not 500E raw power, but enough for regular speeds. Plus, it was a luxury car when introduced, so for a daily driver, it's nice that it's fully loaded.
The wife drives the 500SL almost exclusively, so I never get to drive it (unless it's almost out of gas or it has to get serviced).
Beginning to enjoy the ML a bit more, as I am doing some work on the W124 right now, and wanting to take my time. So now I'm driving the ML to work, liking the heightened view like all of the other trucks and SUVs I see.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car