What's the best way to transfer large files to a fellow Mac user?

Question

… ftp, file sharing, dropbox…?

Answer 1

Is this a one-time transfer?
If so, what is your email file size limit?
Depending on the limit, try Compressing the file.  If that doesn't work, try splitting the file into smaller chunks with Tar.
In Terminal (assumes file is on Desktop, if not, just change cd)
Note: don't use full path in filename unless you want it stored in the Tar
This will break the file into 10MG chunks (-L10000):
  cd Desktop
  /usr/bin/gnutar -L10000 -cMv --file=tar_archive.{tar,tar-{2..25}} [FileToTar]
     to Extract on the receivers end:
         /usr/bin/gnutar -xMv --file=tar_archive.{tar,tar-{2..25}}