I don't know which I'd rather teach, because I'm not a teacher (nor would I like to be). From the student's perspective, however:

Not completing assignments is an extreme case. More often than not, it's mere procrastination.

Anyways, from my personal experience: A seven page essay is due three weeks from now. A kid without much intelligence might work dilligently on it all this entire time, soliciting comments on points of dispute with the TA, putting the time in, etcetera. I, on the other hand, will probably write the essay in two hours the morning that it's due.

Being able to produce something with quality and polish in a limited amount of time allows me much more time to do whatever I feel like, pursue my outside interests, in the meantime; It allows me to succeed at collegiate studies without actually making them a focus or significant investment of my life.

I know which student I'd rather be.

I rather teach the diligent student. I doubt that you can get much out of writing the essay the day it is due. Sure, studies do not have to be the center of your life, but there is a fine line between that and utter carelessness. The diligent student shows me that he is interested in learning while the other shows me he does not give a damn. It is not only whom I rather teach, but I know who is going to get more out of his education.

The father of one of my friends groups students into 3 categories:
1. the race horse-- intelligent
2. the work horse-- diligent
3/ the donkey-- slow, neither of the above

I think any good student should be at least a work horse. A race horse that does not work is not commendable, but a work horse that is not very smart is usually a good student.

As a future teacher, I think that I must be able to work with all types of students. While the diligent students seem to be the easist to teach, the intelligent ones have to be handled carefully. The key is to provide other outlets for the intelligent students so that they do not grow bored or become a nuisance in class. For example, you could recommend other books that they might enjoy. I think a good class has a blend of mostly diligent students with a few intelligent ones.

""I rather teach the diligent student. I doubt that you can get much out of writing the essay the day it is due.""

Well, this depends -- is your goal to learn through the essay, or simply to convey what you've already learned to your teachers? It depends on the course, but especially with general ed classes, it tends to be the latter. I know what I know, to put it that way, and if I care to know/learn something, I know enough to seek it out successfully.

For classes like philosophy, especially, I view essays as more a matter of laying out what I've already learned and know than an opportunity (which I don't need) to explore something deeper.

For history, it works rather differently -- there's always more depth to be found. But for classes in the realm of philosophy... essays are best gotten out of the way sooner rather than later.