How powerful is Ghost Rider ?

i think he could beat most any who oppose him easily even without the penance stare 

Ghost Rider uses the Penance Stare on Joker and then gets a headache.

Joker then gives him poisoned Aspirin and Ghost Rider dies. The End.

Sincerely,

Depends on how much Johnny's in control. When Johnny's in control, and the 'safety's on', he's strong enough to go toe to toe with quite a few heroes in strength.

When the safety's OFF, and the Rider's in charge, well... Let's just say there's a reason even the Sorcerer Supreme stays clear of the Rider.

Especially after Strange and Johnny's little staring contest.

@Jokergeist: Ghost Rider uses the Penance Stare on Joker and then gets a headache.
Joker then gives him poisoned Aspirin and Ghost Rider dies. The End.
Sincerely,

This

In one Fantastic Four The animated series episode he was able to take down Galactus without breaking a sweat.