I have many slants including an almost brand new 301. My sentimental favorite of all my machines is my 401 and I like sewing with it.
But my favorite quilting machine is my 15-91, followed closely by three vintage Kenmores - all vertical needle machines. I do anything heavy on these machines because the slant-needle machines are more prone to needle deflection/breakage than the machines on which the piercing is happening straight up and down.
I do some piecing on my 301, but not usually free-motion quilting because of the deflection issue.