We refurbish sewing machines so have had a number of them on my desk. Our average time for work with and on them ranges from 6-15 hours so we know it is in top condition and what a machine can do before it leaves us.
The 301 is great as far as ease of use and visibilty of the needle due to the slant shank and the off set of the tension dial It is strictly a straight stitch unless you locate a zig zag attachment which if you can find it will run anywhere between 50.00- 400.00. I have not sewn with one of the attachments so can not speak to the quality of the stitch it produces- it creates a zigzag by moving the fabric from side to side. I like the 301 machine, great stitch quality and easy to manuver fabric with excellent speed control.
I grew up with a 401 and thought for years that was the cream of the crop. It also is a slant needle with more options as far as stitches. Having said that I still believe it is a very good machine but now have more insight. The two center dials which need to be changed with stitch selection can be touchy and even difficult to not possible to set if the machine has been abused.
Out of the 400 series I would seriously suggest the 403- much simplier to set- the same cams fit it as the 401. Also would recommend the 501 also easy to handle and has an added feature of a dial inside the faceplate that allows you to set the presser foot tension witout guess work out of it. All three are very good and will meet your needs for years to come if they have been properly cared for. Recently someone refered to one of our video demos as an example of what the machine they were selling was capable of. My husband made a very good point- it's like buying a used car- depending on the life, care and maitainence a car/machine has had you are not able to truely access it by what another one is capable of. We have sold the 301, 401, 401, 501 within the last few months and have others soon to be so continue to find features we like about each model.