The best replacement for arson is pyromania.

The best alternatives to arson are rated as following:
★★★★★  pyromania
★★★  incendiary
★  theft
★  mischief
★  aggravated arson

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Speaking about arson, one probably shouldn't forget about homicide.

Other search terms related to arson and their ratings are:
★★★★★ homicide
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Google Trends

Scale is based on the average worldwide traffic of arson in all years. Click on graph for more.
arson
pyromania
incendiary