The 310 is a slant needle machine, so it's feet are only interchangable with the other slant needles - the 400s and maybe the 500s.
The 185 can use any short shank attachments you have laying around.
In my book, the 301 wins. My 301, AnnieRose, is my piecing and FWQ machine. She does a great job at both. She is also light enough to take in public.