As DM do you match targets or completely go random?

[Ragnorakk]

Total hardcore application of random targeting and BTB round length sounds fun.
In general I've used Intelligence, and whatever situational considerations prevailed.
Applied across the board, it could be just as frustrating for players as DM's used to 'running' their monsters combat decisions. But it feels more gamey. I think it could be
easy to argue that the first round of most melee encounters might benefit (unless there's
ambush, foreknowledge of situation) - that evaluation and selection of targets couldn't happen until they had 'sized up' the opponents. That is usually how I end up playing many less-than-intelligent monsters anyway - totally random first round, then if some target stands out, maybe try and hit that one.