atool is the command-line equivalent to WinZip-style programs—and it just works.
Most importantly, the aunpack tool (for extracting files) will first check the number of items in the archive root. If there is only one item (a directory or a file), it gets directly extracted to the target directory. If there are more than one, they are extracted to a new directory.
For example, if A.tar.xz only contains fileA, aunpack A.tar.xz will extract fileA to the current directory. If B.tar.xz contains fileB1 and fileB2, aunpack extracts them to a directory called B. This has saved me countless times from extracting truckloads of files to my home directory.