Scott, a Danforth or Fortress is the best bet for a stern anchor.
A couple of reasons.
First the Fortress can fold and store easier in your locker. It is also fairly light. However, it is a bit more expensive.
The Danforth is heavier and holds well in most conditions as a stern anchor (as opposed to a bow main anchor). It also stores sort of well, but much better than a Bruce or Delta.
Note: both anchors (especially the Danforth) will tend to skip in weedy conditions commonly found in GB around Beaulsoliel Island and so on.
On the assumption that you currently have a Danforth as a main anchor, change it out for a Bruce (or Delta) and then use your original Danforth as a stern anchor.
The Bruce or Delta will hold much better in most conditions you are going to see including Thorah Island which can have a rocky / boulder bottom but equally well in sand bottoms.