I own 4 featherweights, 66,99k,15-90k and 201k and use them all.
All of the machines you mentioned sew a wonderful straight stitch and that's all they will do.
The 66 & 99 Singers are NOT featherweights, they weigh about 30-35 pounds, make a great straight stitch. People have figured out that we like older machines and are asking outrageous prices. I wouldn't pay any more than about $40 for the 66 & 99.
The 221 and 222 are, the latter is a free arm and more expensive than the 221. The 221 and 222 weigh about 11 & 12 pounds. The 221 featherweights go from $200 to lots more. The 222 usually starts about at about $500 and goes up from there.
Added pictures of some of my machines so you can see the difference between the models.
Sharon W.
1954 featherweight
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99K
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66 red eye
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