I don't know which model years had the least amount of problems, but from my experience, we had two 123's (82 and 83). The 82 was a European import with manual transmission. When I sold it, it has 240K miles on it. The 83 automatic which is still being used in my company is now pushing 350K miles and still going strong.
You have to get used to zilch power (even with the turbo kicking in), but they do run and run and run - you get the idea.