BCrypt vs Key Stretching MD5 Ars technica posted an article about the latest in cyber warfare from the stuxnet crew.

They key stretched MD5 by iterating it 10,000 times.  It seems to be effective at handicapping HashCat's gpu acceleration.  Had I been them I would have used bcrypt instead.

Why/When would someone prefer streched-md5 over bcrypt?
How is bcrypt superior to a strectched-MD5?

If you've got the math power $MD5(password)^n = bcrypt(password)$ solve for $N$.
Any time there is a choice and password search is an issue, one should prefer scrypt or perhaps bcrypt to stretched-md5, or even PBKDF2.

The reason is that scrypt and bcrypt provide better security, by requiring a bigger investment in hardware (in particular, RAM) for the would-be password cracker, assuming parametrization yielding the same runtime for legitimate use. If enough RAM is available in legitimate use, the additional security obtained by using scrypt can be quite dramatic. See the following table from the paper Stronger Key Derivation via Sequential Memory-Hard Functions defining the Scrypt Password-Based Key Derivation Function.