Hard to go wrong with shield!
Shield Defense + Dark Melee has long been considered a great pairing on any AT, really. ToF was updated to an AOE, which is nice when proc’d out ( @SomeGuyhas a great set up for this on his scrapper). DM also brings a heal, which is something Shield Defense lacks.
I personally had a Psi Melee/Shield Defense Scrapper that I love. I could see the pairing doing well on a tanker. Shield Charge + Mass Levivate = a lot of fun and baddies on their butts.