Ok - All than:
WC 1+2 - Rapier
WC 3 Excalibur - Becouse its fast, has 4!!!! Tachyon guns and 12!!!! Missiles which gives it an unparalleled Offensive Punch (Even the Thunderbolt isnt armed that heavily excpet of the torp).
WC 4 Dragon - Its cloaking realy comes in yousefull from time to time...