I play a lot at Whitby Airsoft field. Sam's a good host there.
Though I notice a ton of green never call there hits. It's in-evitable, guess they are to comfortable :P
What do you look for in a field?
Uniqueness. Main reason I play at Whitby is because of the forest/woodlands theme.
What would it take to keep you coming back to a field?
Price, community, people, location. Whitby Airsoft is closer to me then most fields, great hosts and great people. Food is quite good too, and gas is cheaper out there then Toronto. At $10 you can't complain, really. It's also very close to the 401 exit.
What do you look for in a game host?
Confidence, what they are doing, adapting to player suggestions/recommendations/game plays.
How important is field safety to you?
It's obviously important, but there are risks for playing in difference scenarios. I.E @Whitby playing in a forest you are self-prone to poison ivy, fire ants, mosquitos, spiders, and other stuff. It's really up to the community and players to be well aware of their surroundings. Often when playing other teammates would say "Hey don't go there, there is poison Ivy over there." People like those guys are awesome.
I plan on trying Hill437 this summer with Bad Karma, and other friends who have visited there.