They all will have variations. The data is only as good as the lab/researcher collecting it. The ASTM JCPDS data files are best, but very expensive. I like RRUFF, but it is still in development
The best is the one that you calculate from a crystal structure (data files for a lot of minerals, even though not all, can be downloaded from the American Mineralogist Crystal Structure Database - check link on each Mindat mineral page).
The RRUFF database offers measured downloadable datasets which might be helpful if there is preferred orientation.