I have to say that Ghost Rider absolutely wrecks Spawn. I know most people will try and argue this with the typical Spawn counterargument; "Spawn beat God and the Devil and banished them from this realm", and while this is true, it was 100% circumstantial. The Man of Miracles, the true omnipotent of the Image-verse, was tired of God and the Devil acting like petty children, so he stripped them of most of their power, sealed them in the bodies of two mortals, and then gave that power, plus the power of the Greenworld to Spawn so he could beat and hopefully humble the bratty beings. We know he didn't keep this power, not only because MoM stripped it from him sometime later, but in a later battle with the forces of Hell, Spawn went up against the Devil and had his ass handed to him.
Now, onto why Ghost Rider wins: Ghost Rider is physically more powerful than Spawn, being able to hold his own against characters like World Breaker Hulk, who's very footsteps threatened to shatter the Eastern Seaboard of the USA. He's had more experience in battle, and has faced down tougher opponents without needing help from a true omnipotent, just look at his battles with Blackheart or Mephisto. His weaponry and Hellfire will also do significant damage to Spawn. I know they're not "Holy weapons forged in Heaven", but two things on that; One: That's not the only way to kill Spawn, as Al Simmons used his suit's demonic powers to kill himself and let someone else take over the mantle of Spawn. Two: That hasn't stopped Ghost Rider ever. Characters like Blackheart and Mephisto, powerful demons well above Spawn, have been badly damaged by Ghost Rider. This may seem like a good idea on the surface, but this is a massive stomp for GR if you step back and look at it.
Plus Ghost Rider has done the very following.
-Hellfire body and indestructible skeleton make it so that stabs, slashes, and gun wounds won't hurt him, nor can he be torn apart
-Spawn has no heavenly properties, thus he can cannot kill let alone hurt Ghost Rider, which are the only things that can kill him
-GR's immune to all kinds of fire
-Only the Hulk in his strongest form The World Breaker (Who was so strong that just his footstep threatened to destroy the entire eastern seaboard and was shaking entire continents) was able to knock him out...for two seconds before he was back up on his feet and kicking butt again like nobody's business, even then Ghost Rider was tanking his punches
-GR defeated Satan, Mephisto, and Blackheart with only half his power
-GR has been through hells far worse
-Far vaster fire manipulation, from emitting it on his body to molding weapons with it like chains and guns
-At full power, Ghost Rider is cosmic level, in fact, he's a high tier character in the Marvel Universe.
-If Ghost Rider wanted to, he'd incinerate the entire earth
-Single handedly defeated a fully fed Galactus with the penance stare
-Has stopped Hell's invasion towards Heaven many times