Is there any reason to watch these in order. The netflix DVD came with Android of Notre Dame(which I think is the fifth one?) and I was wondering if there was any reason I shouldn't watch it before the others.
No, they're separate movies. If anything it's probably best to watch the less disturbing ones first and leave the harsher ones for later. Obviously, if you can watch the 'making of' episode which is one the Flower of Flesh and Blood DVD at the very end cos it shows the special effects that were created for the films and behind the scenes footage from some of the different films and it will spoil them for you.
You can probably read other people's opinions on the boards about which they think is the 'best', generally Devil's Experiment and Flower of Flesh and Blood are considered the most harrowing so I'd leave them for last. He Never Dies is more cartoony, less serious in tone but just as gory. Mermaid in a Manhole is supposed to be really gross and psychologically unsettling rather than the blatant sadism of the first two films.