Really different situations, so hard for me to rank them.
If you are looking for a guy who can deliver steady points, that would be Guice -- once healthy that, is. His floor might be low because the Skins look terrible offensively, but seems to me he has a chance for anywhere from 50-70% of the carries once he's back.
Snell has value in the here and now -- but once Jaylen Samuels is back over the next game or two, I think Snell is mostly relegated to the bench and only has value if Connor or Samuels go out again. And given their health history, there is a chance of that.
Armstead would be a season saver and pure lotto gold but doesn't have value now or through the last half of the season, and is wholly dependent on a Fournette injury.
Such different situations, so I would say if you are looking for a guy to contribute now, Snell. A guy you can hold but will need to potentially contribute as a flex later, Guice. And a guy you can afford to hold on to an not play at all unless/until he hits as a pure lotto ticket, Armstead.
Three guys I am trying to rank are Guice, Samuels, and Hunt. I will have a need for a flex contributor starting ~Week 10/11. All three of these backs, if healthy, will see some carries. All three have a path to get a large share of carries if the starter falters or they simply flat out outperform them. So by comparison standards, I think this group is more apples-to-apples.
How would you rank them if you were looking for a potential flex contributor with upside?