Actually all of the available online reports are using pretty the same data sources, basically it's NMVTIS database. The difference is how they format and present that information to you. Plus, they put some stats data like average market price, manufacturer recalls, etc. One should always remember that there won't be any info on accident or on other issue if the owner has not reported it to authorities / insurance company. You may compare all of available reports and see how identical they actually are:
Carfax -
https://vini.az/en/report/SAMPLE-CARFAX
Autocheck -
https://vini.az/en/report/SAMPLE-AUTOCHECK
Almost raw NMVTIS -
https://vini.az/en/report/SAMPLE-SALVAGE