Windows only: If you're looking for extremely granular control over file copying, and fewer failures, you don't want to miss RichCopy.
We're big fans of replacing the default and clunky Windows file copier with more speedier solutions, like Teracopy or FastCopy. If you're looking for speedy transfer and detailed control over all manner of things, like what files should be copied or overwritten based on age, size, attributes, or even the security settings for the directory they are in, RichCopy has you covered.
RichCopy doesn't have shell integration, unfortunately, like many of our favorite replacements, but given the kind of detailed tweaking you can do in RichCopy, you'll likely be opening the application to tinker in the sub-menus anyhow. RichCopy was previously an internal tool for Microsoft developers to use, but now has public release. There's no serious support for the tool, and it falls into the as-is category. That said, I didn't have any problem copying 15GB of data from one drive to another in a matter of minutes, thanks to RichCopy's snappy multi-threading support. RichCopy is freeware, Windows only.