All ways of patroling are good, depending on the situation, and on the unit you are patrolling.

 

Usually, warriors want the circular patrolling type, so they can not get targeted by a lightning or a blast.

Preachers want to stay still, or using a line patrol (from one point to another), to cover a bigger area.

Firewarrior's best type of patrolling is probably the same spot patrol (click more than twice in the same spot, holding Ctl+Alt). They are usually good in groups of 2 or 3 firewarriors.

The shaman should never be stopped, as the will be an easy target to enemy blasts or lightnings, so make sure you patrol her aswel. The best way is usually using irregular patterns.