.....slight "zig". Where/how. Don't have a microscope....don't want to buy one either......

I have found that my Singer 301 is excellent for the job. It is a basic machine forward and backward only. The feed dogs can go down so you can machine quilt, Very little goes wrong with it as it is a basic machine. If you are a speed demon, this is the machine for you but you have great control of fabric.
It is like a souped up Featherweight--

I've been quite happy with low end Brother machines. Usualky I end up passing them on to friends or family needing a machine. Lol!

However I will hang on for dear life to my Featherweight! I use it almost exclusively.

Love my Singer 15-91. (Paid $80 in a cabinet with no attachments.) And love my Pfaff. I totally agree, I am also spoiled with the IDT.
My next machines will be a Singer 201-2 and a Juki 2010Q.
If you do go the vintage route I strongly recommend purchasing a walking foot, wished I bought mine much sooner. Found it cheaper online vs local store. Good luck!

I have the Brother XR9500, I've had it for a while and love it. Have used some of the decorative stitches and it works great. I bought it as a back up and to take to classes because it is lightweight compared to my other machines. I also have a featherweight, I use it but it is mostly for looks. I like the Brother because you can just about take it to any sewing machine repair shop for service and parts are usually available. With the featherweight service and parts in my area are hard to come by.

The 301 is called the Featherweight on steroids. Mine came with a "Zig-zag attachment". It works well if the fabric is firm enough or starched. It also has a buttonholer that works much better than my $2,000 Bernina.

I use a Babylock Jane for straight stitching. Jane handles the bulkiness of quilts, denim, leather, etc with ease. She is easy to clean, and if purchased new, quite a few different feet come home with her. Some of those feet included a hopping foot for FMQ, a walking foot, and a 1/4" foot. Jane is mechanical, so don't expect any means for computerized design or s stitch regulator or even a zig zag stitch. Jane is completely a straitch machine with a 9' throat. Check out your Babylock dealer....store demo models are being sold to make way for newer products.

Vintage machine for straight stitching hands down. My favorite is either the 15 or the 301. I've purchased many straight stitch machines for $20 and have been given some. Don't spend big bucks for a straight stitch only machine. That's money that can be spent elsewhere.

I have a cheap Kenmore and I love it...

Sorry I have to disagree with you about the vintage machines only being for collectors. I have a 201 and a featherweight that I love and use all the time plus an older Pfaff that I wouldn't trade for anything. Many ladies in my quilt group also have and use vintage Singers regularly. So far I have not had to have any of them serviced, my husband checks them out for me and keeps them cleaned and oiled. By the way I don't consider myself a collector. Forgot to mention that I take the featherweight or the Pfaff to retreats or my quilt group. The 201 is way too heavy and is in a cabinet so it stays home.