I think you've boiled it down to some great choices to fit your needs. There's a lot of value for the money there. Any one of them will work nicely.
That JRB Greylock's introductory price at only $15 more than lowest 40ºF quilt price you have highlighted is a great deal for a 20ºF quilt.
“I think that when the lies are all told and forgot the truth will be there yet. It dont move about from place to place and it dont change from time to time. You cant corrupt it any more than you can salt salt.” - Cormac McCarthy