It is very hard to find a more successful physicist.
- One has to remember that before Penrose-Hawking singularity theorems, people were generally focused on "finding a particular solution" to Einstein's equations. To put the emphasis on the "properties of any solution" was a major shift in mindset. Under very generic conditions, singularities are unavoidable. This is contrary to the belief held before in particular by the russian school, that the singularity was merely a consequence of the perfect symmetry assumed before collapse. The perfect symmetry is not necessary. Even worse, assuming a "positivity of energy", there must be a singularity somewhere.
- Beyond classical theorems, we do not have many formulae involving both G and hbar. One of the very first question anyone will ask when presented with a theory of quantum gravity is "does it reproduce Hawking's entropy ?".
He deserves his status of world first class physicist just for those two contributions, and independently of anything else he has been involved in.
There is no doubt that he was a very successful communicator as well. Very few featured in the simpsons for instance.