I didn't really start watching Dr Who until the new series started in 2005, so I'm not familiar enough with any others to say. But that is definitely an interesting question.

OMG, and now I really want a "buddy cop" episode with pretty much anybody and the TARDIS. That would be the bomb.

That reminds me of that Doctor Who joke:

As everyone is giving advice on where to start, I'll put in my own two cents.