Here are some macros I used,

This macro targets enemies marked with signs 1-5 in sequence or assists your focus target (primarily for dps using Tanks as focus) or target nearest enemy if none :

/macroicon "Auto-attack"
/targetenemy
/target <attack5>
/target <attack4>
/target <attack3>
/target <attack2>
/target <attack1>
/as <f>
/facetarget
/wait 1
/battletarget

*/battletarget will target the closest enemy that is currently attacking you and it is added to prevent the targeting to be in limbo state as when enemy dies with sign attack1 still on, it will not fade off immediately thus it will always attempt to target 1, causing no targets to be selected*

This macro below is to quickly target and re-assign signs 2-5 in sequence to 1 to solve limbo signs problems (or you use it to assign attack1 to the target) :

/target <attack5>
/target <attack4>
/target <attack3>
/target <attack2>
/mk off <t>
/wait 1
/mk attack1 <t>
/target <attack1>
/facetarget