The 301 will be the better of the two for free-motion quilting because you can access the bobbin even with a quilt in the machine. The drawbacks are the slant needle, which makes needle deflection more likely. It has great piercing power, but when you hit a seam, the needle is going in at an angle, rather than straight down.
The 201 has even more piercing power and needle deflection isn't as likely, but getting to the bobbin while you have a quilt on the machine is not easy. The bobbin is on the smallish side, so if you're free-motion quilting, you'll be be changing bobbins about 50% more often.
I have both machines and a couple of 15-91's. I would take the 15-91 over either of the others.
Vertical needle, access to the bobbin, large class 15 bobbin and very powerful. Not quite as quiet as the 201, but not as loud as the 66 or 400/500 series. I actually like the sound of the 15. :)