I have all three....
Four if you count paper and electronic FSM versions...

The "Bible" by Stu Ritter is a great primer if you are not much of a DIY type. More of a chatty coffee table book rather than a book you take out to the garage.

Haynes/Chilton books are a nice addition to a factory manual because if a service was covered in a concurrent manual, it's left out of the factory service manual. The factory assumes you have other series manuals as well as the W124.

Electronic tends to plug some of these holes, but still....

Jim

__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles