patricej

this is the free motion foot i use.
what makes it so useful is that you can adjust the distance between the foot and the quilt sandwich.
it also doesn't hurt that it's 3 feet in 1.

https://www.sewingmachinesplus.com/j-202001003.php

(note: the link is just so you can see a photo and the features. not a sneaky advertisement for this vendor. lol)

shop around because the price for this foot varies widely among vendors.

it came with my janome mc8900.
it's so great i bought a second one to use on my brother dream machine.

themadpatter

Thanks everyone for your answers! I've used the darning foot on my Necchi, and I think its what we would call a hopping foot and I didn't really like it, so I'm glad you discussed that, too.

Becky's Crafts

I have a Brother NX2000 sewing machine and I love my "Big Foot" (from Nancy's Notions) with the large, clear foot so I can see where I'm going & where I came from at once. I buy the low shank for my NX, but they have the high shank ones also. The large bowl on this foot also helps to stabilize the quilt while you're quilting.