I have messed with a couple White machines lately - very nice - even the newer ones. I think I have two of those older rotary ones somewhere in the shop - haven't messed with them yet.
How closely are the 1980s plastic White machines related to Janome? I noticed that the White and the New Home (with Janome label) thread the same. I can't look at them any more - sold them.
The other machine I'm impressed with has been some of the Montgomery Ward. That WM 15 clone was the best one I've seen made by Happy - that presser foot lifted higher than any I have seen. Amongst the really dirty hoarder machines, I had an old white, chrome and ORANGE 1970s - it cleaned up pretty nice though - it had a nice variety of stitch features and a good amount of attachments and the manual - worked beautifully - sold it. Right now I have a later all metal one probably late 60s early 70s that does straight & zz - center needle. Very nice machine - made by Happy - says so on the bottom.