I think that they're both good and I incorporate both. When performing a new exercise, or at least a variation on one I'm familiar with, I usually work up to a max-ish set. For example today I did high box squats and worked up to a big single. This gives plenty of volume as you work the way up the weight. However, I also find it beneficial to work at sub maximal weights for sets across to really hit home the intensity and volume as each set is tough.
I find the latter better for a more linear style of progression, or if not then one based around set percentages where the weight being performed is pre-determined by 1 rep maxes and the like.
For example, when I'm training with someone, I like to have them work up to a heavy single, possibly a PB or fairly close. Then I have them drop back and hit 5x5 with around 80% of what they achieve. This way you get the best of both worlds. Obviously this is just a one off, but it gives you a slight idea of what I mean. Ish.