Avalana, I can vouch for the guys at Rebel Ads without hesitation (they responded already in this thread). They represent several high quality properties, and some networks as well, plus can deliver a nice quality traffic stream if you prefer some advertising in your budget.
Also check out Nurgle/Marcy... they have
many quality websites and are great to deal with. Old school people with a network of sites that are focused on making sales (they don't build a bunch of sites just to sell links on them). This is one of their threads here:
https://gfy.com/showthread.php?t=1087807