I like both units, but the points investment for
DC is better for 5 models and as a whole they are almost as resilient as the Sanguinary Guard when not being hit with
ST:8 weapons that don't ignore their armor save.
Also, Death Company have fearless, rage, furious charge, relentless, and feel no pain.
Sanguinary Guard have Furious Charge and Master Crafted weapons.
Weight of attacks also heavily favors Death Company. Five models puts out an absolutely withering number of attacks. The more saves you force someone to make the more they fail.
I love Sanguinary Guard, but they need a baby sitter in my mind to really come into their own, specifically a Sanguinary High Priest, or Chaplain. This allows them to hit more often with their fewer attacks per model in both instances, using different mechanics of course, and also in the case of the Priest gives them
FnP too. If you're going to field Sanguinary Guard they almost have to have the chapter banner to give them the bonus attack, but that sadly increases their points even more.
Were I to run Sanguinary Guard, I would kit them out at 5 models, possibly 6, with 3x or 4x Swords, 1x Axe, and 1x Power Fist + Banner.
That grants them 3 attacks base (2 + 1 for the banner), 4 attacks on the charge, master crafted on all but the power fist model. Attach a Sanguinary Priest with a Jump Pack and whatever other wargear you wish and they'll mulch
MEQ or worse. Sadly they have to avoid
TEQ and other melee focused units that ignore their armor (Thunderwolves, Wulfen more often then not).
The downside is the Death Company will, more often than not, be a bigger threat to more targets, often at a cheaper price point for equivalent number of models and without requiring an attached
IC, though a Chaplain goes with the
DC so nicely I will freely admit.

That's why people tend to prefer them. At least in my experience.
Hopefully that helps.
Take it easy.
-Red__Thirst-