T-Meg, depending on your scope of work, I think its important to having all three items, but I agree with Redsky about the pocket tester...make sure you buy a high quality non-contact tester. I own both a Pyramid(made by Amprobe)and I especially like my Fluke. The Fluke is highly sensitive to the point is is sometimes difficult to acertain the status of a wire when others are in close proximity, but this is actually a good thing if you think about it.
Electure is also correct about a DMM's extemely high input impedance(quality ones anyway)causing occasional misinterpretations. I strongly suggest the Fluke 87III, an industry standard, and although pricey in the neighborhood of $350, it IS an excellent choice and has useful features for advanced troubleshooting.
I think a "Wiggy" has good utility, also for its lower input impedance which, in a desireable way, can slightly load floating or hi-Z circuits in order to obtain true reading. An old Simpson 360 VOM can do the same.
Thirdly, one should also have a good clamp-ammeter(I prefer a Fluke but there are other brands equally good), especially if you work with motors & drives.
