In your experience, what's the best way to test your game? My next game I'll be looking to test with a larger audience and I'm looking for the recommended way to go about it.
The best way is to pay them. You could try running a cash contest try to get a few 100 people to play it.
Have you considered a softlaunch in a territory like Australia? You should be able to generate those kinds of numbers organically.
What do you want them to do? I have used SurveyMonkey to get people's opinions on screenshots, but that's not testing the actual game.