Found a similar question about the difference between QAPlug-FindBugs and FindBugs-IDEA, but not about CheckStyle...
I think (from previous experience) with these plug-ins that one difference is that the QAPlug's CheckStyle version seems to be behind the CheckStyle-IDEA's CheckStyle version (I'm not referring to the versions of the plug-ins, but of the version of CheckStyle that's embedded in them).
Anyone knows of any other differences between those?
Advantages of CheckStyle-IDEA over QAPlug – Checkstyle:
I haven't noticed any use case when QAPlug is better.