I've found the Bombardment Cruiser far superior and near indispensable. Those standard ship missiles, with their SAP, P traits mean they dole out mountains of crits per salvo! And with SAP, even hull 6 ships will feel the hurt. Changing those out for Flash Missiles reduces your penetration (Only AP vice SAP) but the addition of DD just makes things all the more painful.
The Strike Cruiser seems, in theory, good; however, I've never had that much success with Railguns, and the Strike Cruiser has always struck me as too sluggish and slow to get the best use of its broadsides.
I typically use Marathons armed with Flash Missiles, backed up by Apollo Bombardments with Standard or Flash Missiles. Marathons are hunter-killers, Apollos try to get as many ships into as many arcs as possible to dole out the crit pain.