$ being a factor,and new at quilting, which of the 3 would be the be my best investment? And does the sid move the top fabric like the walking foot?

I guess it depends on what you want to do. I use all three feet frequently. If you are just starting out, you could pass on the darning foot. Most people tend to get the basics down before attempting FMQ. The walking foot is great to have for other uses, not just quilting. It's handy any time you have to sew something thick, such as purse handles. The Stitch in the ditch foot isn't a necessity, but I like using it...my SITD is more consistent.

It all depends on what you want it to do. I bought the walking foot first because I could stitch in the ditch with it, and it really did help keeping all the fabric moving together, even when I am piecing. I got the darning foot later, because it was cheap and I wanted to try FMQ. The SID I got with the new machine. Wanted to make sure I had all the bells and whistles to maximize what my new machine could do.

Of the three, I would say that the sitd foot is the least one I use. You can stitch in the ditch with your walking foot.

I don't use a walking foot...I have a roller foot which does basically the same thing and was much less expensive to buy. For free motion quilting you will need the darning foot. The darning foot will also allow you to darn socks if you're so inclined and to do thread embroidery one stitch at a time on your machine. I don't have a SID foot but I'd like to get one just to try it out for small projects that I don't want to set up on my long arm.

I think a walking foot is the best investment, a darning foot is only for FMQ and if you are a new quilter you probably won't need that for a while. I have a sid foot that attaches to my walking foot which I use all the time, but only some machines have that available. (I have a viking)

Agree with above...I'd buy the Walking foot first...I also SID with it and put my binding on with it. I bought a SID foot and never use it because I want my fabric to move underneath and that's what the Walking foot does.
I had to buy the FM foot when I wanted to learn that but that came much later when I figured I'd stitch with it and learn FM. Still not very good at it but still give it a try now and again.

a stitch in the ditch and a walking foot are the same thing- a darning foot- sometimes called a free motion or a hopping foot is used for free motion quilting- a walking foot is used for straight lines- so it depends on what kind of quilting you are doing

I would go with the walking foot first and then if there is a stitch-in-the-ditch sole for your walking foot I would get that, and then lastly the darning foot.

With the walking foot you can piece, stitch-in-the-ditch, straight line quilt so that would cover quite a few things that you might do as a new quilter.

Do you already have a 1/4 inch piecing foot? That would be my first purchase. After that, a walking foot.