The EFEC tanks are the best. Period. Their speed combined with their special makes them superior. The Vircator special is the equivilent of three and a half hits (three hits to take out the shield and a half a hit because it takes out half a squad on lesser units).
BLOS is overrated. As a Russian, I kill all BLOS tanks. JSF players tend to think their tanks are a god. They will dash real fast when they know their BLOS tanks are getting killed.