Wifi or wired? (Wired POE is always better if you have the option.) If it's going to be WiFi, do make sure you have a good reliable signal where your cameras are located.
Amcrest has a pretty good selection of cameras in both categories, and we have two suggestions on the Indiegogo FAQ tab that you could start with:
"The Amcrest IP3M-954E (PoE) and Amcrest IP3M-943B (Wi-Fi) are good general-purpose outdoor cameras. [...] We have absolutely no connection to Amcrest and get no kickback for this recommendation."
A note about Amcrest ... If you buy some other model, make sure you're getting one that supports RTSP. All cameras sold as "Amcrest" do support RTSP, but some of the cameras sold as "Amcrest SmartHome" do not. We're happy to help you check on this before buying if you're unsure of whether a camera will work.
Amcrest cameras are made by Dahua, which is the second-largest camera manufacturer in the world. Many of our users also use Hikvision cameras (Hikvision is the largest mfr), but they're a bit more unfriendly for nontechnical people. S3VC has also received some good reviews, although we have not tried many of the cameras in their lineup ourselves.