It seems you get more if you clear it faster. I finished it alone with like 4 minutes or less left at one point after the host quit during wave 2 and I got only 56. Finished it with 5 minutes and got around 80-90. I also saw a screen of someone getting over 100.
So, yeah, it's probably the best if you actually play well enough.
Does it give you extra for your first clear? Cause...
This was with Shadow Knight killed but only like ~4 minutes left when we killed the boss, I think. So it's possibly just random drops? (Or else, yeah, a first clear bonus.)