From the old system to the new:
scp -r ~/* zeugma@newssystem:.
If you're logged into the new system:
scp -r zeugma@oldsystem:* .
If you just have the hard drive from the old (note:$OLDDRIVE = whatever directory it is currently mounted as), "cp -r $OLDDRIVE $HOME
My bookmarks file for Firefox is essentially the same file that I've transferred from one system to another starting over 20 years back. Yeah, Firefox now stores the data as a json file, but it started as bookmarks.htm back in the day, and I've been able to maintain it without significant loss for that long.
Part of that is that I'm religious about backups. Part is that maintaining consistency with linux is easy.
#18 ah yes the old zeugma command....
Greek to me :)