While there is no way to know for certain which of these events was more important, I do generally tend to agree that the Reichstag Fire was more important than the Enabling Act simply because (in my view) the Enabling Act would not have been passed had it not been for the Reichstag Fire.
Hitler became chancellor of Germany on January 30, 1933 when President Hindenburg was persuaded to name him to that office. Hindenburg’s advisors were more afraid of an alliance between conservatives and trade unionists that Chancellor Schleicher was trying to create than they were of Hitler. Therefore, they got Hindenburg to replace Schleicher with Hitler.
On February 27, 1933, the Reichstag Fire happened. Hitler immediately declared that the fire was part of a communist attack against the German government. Under Article 48 of the Weimar Constitution, Hitler issued an emergency decree in which he suspended civil liberties in Germany. This decree remained in effect until Hitler’s death.
On March 23, 1933, Hitler got the Reichstag to pass the Enabling Act which allowed him to rule by decree (rather than having to get laws passed by the Reichstag). Hitler was able to get this law passed because all of the communist members of the Reichstag had been arrested under the emergency decree. From here on, there were no legal limits to what Hitler could do as leader of Germany.
Clearly, the Enabling Act gave Hitler a huge amount of power. However, I would still argue that the Reichstag Fire was more important. It created the climate of fear that would allow Germans to accept Hitler’s dictatorial actions. It also led to the issuance of the emergency decree. Without that decree, Hitler might not have been able to remove the communist members of the Reichstag and might not have gotten the Enabling Act passed. Therefore, I would argue that the Reichstag Fire allowed the Enabling Act to happen. That means that the fire is at least somewhat more important in allowing Hitler to consolidate his power.