Start with the Wire that series has ended so you can watch from beginning to end. Then watch Breaking Bad by the time your done they will be starting the second half of the last season. Then Firefly because you'll need some light airy fun show to cleanse your palette from all the death and despair. The go watch some Walking Dead.
These are all great shows that i love'd to pieces, but have to go with the Wire for best show... ever. Sorry Mash.