A question about intensity

[NZninja101]

By intensity I am referring to the effort one puts into their set, rather than what % of their one rep max they're working with.
What I wanted to know is what do you guy's think is better?
(The scenario is a training split, lets say we're training back with twelve sets of an exercise, normally you would have 3-4 exercises, but for the sake of this question this is not the case)
Would it be better to:
1: Put maximal/near maximal effort in all sets, and as a consequence of this, have to reduce the weight by substantial amounts in following sets in order to complete all desired reps,
OR
2: To avoid maximal/near maximal effort so that by the end of your workout you are using the same amount of weight that you were using in your first work set, (and putting in maximal effort into the final set of course.)
OR

3: Something in-between

[SuffolkPunch]

I don't think near maximal training should have such a big impact on later sets. I would call that training to failure - maximal not near maximal. Which is not a good idea since it will impact other exercises due to your CNS becoming fatigued

I prefer to reduce weight - but increase reps in subsequent sets.

2 will work too provided that you don't have so many sets that you are not using a sufficiently heavy weight. With 2, you are actually increasing the intensity towards the end.