You can never have enough test equipment.You need to use a multi-meter when there is no power on a circut,or how much voltage is actually getting to a component.Some circuts you don't want 12 volts anywhere near,other times you need to place your test light in the circut to act as a load.
Dvoms,Power Probes,12 and 24 volt test lights,fuse-buddys,noid lights,and signal generators-just part of the stuff to hunt down and kill electrical gremlins!

Yeah they really do two totally different jobs. thats kind of like asking "which do you prefer...a wrench or a screwdriver?" (maybe not quite that different but you get the idea). Both are useful in certain situations
I don't think I have ever needed a test light and I can't think of any reason why I would choose one over a DVOM.