Which will give me a Lossless file?
Neither. If the video was recorded in HDV, imported/captured as HDV, and edited as HDV, then the resulting QT file will also be HDV (unless you re-render it) which is not a "lossless" codec. A "standalone" file simply contains all data within your output file container. Instead, a "reference" file contains a combination of "pointers" to data that is contained in the raw captured file and rendered data created during your editing process. "References" file are much smaller and faster to write but require both the "reference" file and the "resource" file be available for use. (I.e., you cannot create a "reference" file and sent it to someone else as an independently playable file.)
If you are using the term "lossless" in the sense of "unmodified," then it makse no difference since the same data is "copied" or "resourced" to both types of file whether it is the raw source data or the rendered data created by your edits within the project.