The Toutatis would probably have more shock value, but the Eris seems the more "expendable", story-wise.
The Solaris seems unlikely, I can't see Byrne getting in position that would allow the GTVA to kill such a vital asset.
IIRC, the new final cutscene of Tenebra shows the Eris being hit by the 3 main beams of a Titan-class destroyer. Even with ECM damage mitigation, that's gotta hurt.
On the GTVA side, I'd say the Imperieuse would be a likely target, to give the player another payback opportunity.