So far I like my 301, "Thelma", the best of all. Her stitches are so even, and easy. I have FMQed on my 15-91, and like her best for those kinds of things. She seems the enjoy the challenge of thick seams to sew through. My 252 is good with simple projects and zigzags. She's in the Living Room in a new-to-me parlor cabinet. I'm still working out the kinks of sewing on a treadle, my treadling isn't great yet, or my 66 Red Eye would be the tops. Of course there is the other 66 Red eye that I need to finish cleaning --- and a 357, a 128-23 hand crank, a 353 Genie, a New Home 70's model, a Wards 60's model, and still others. I try to sew on them in a rotation, but I seem to like the 301 set up , so she gets first chance at any project.
So, really I guess I don't like to have a favorite afterall.