Posted 14 March 2016 - 09:59 PM
Modern digital cameras update frequently so it's probably good to check in again. Basically, when comparing the Weapon Dragon and Alexa/Amira/Mini right now both cameras produce very good comparable images. In general, the Red cameras have more resolution and the Arri cameras have slightly more dynamic range and arguably better color. The Arri cameras are generally less buggy and more robust, but also less customizable. They are also more expensive as are the accessories. While both can now record raw and Prores, most people shoot compressed raw on Red and Prores on Arri. Arriraw is always uncompressed and thus expensive and difficult to work with. You can work with 6k Red footage on a top-spec laptop.
Most larger productions still use Arri (in raw), but that is currently changing now that some studios have begun requiring 4K+ capture. Arriraw in Open Gate sensor mode, the largest area possible, is 3.4k. There is the new Alexa 65 but they are very expensive and rental only, with limited availability. Also very limited in terms of lenses.