Before I go into this post, I just want to add that I don't believe any of these cameras are needed to create the best images. These are what I've owned and have experience with. Your best camera is the one you own.
MY EXPERIENCE AS A RED OWNER
I’d owned a RED since late 2015. I loved the image, the ergonomics and the customer service. RED is the apple of camera gear. They release a lot of products, but keep it going with the amazing customer service. I've shot over 100 videos on RED and have owned the Scarlet, Epic and Epic Dragon . From the day I bought it to the day I sold it, it brought me a ton of work and new clients. It was a workhorse and only had a few minor problems in that 3 year period. I still recommend the camera to everyone. It's such an exciting company to be a part of with a supportive community.
IF IT'S SO GOOD, WHY SWITCH?
This is the question I'm excited to answer and for me this answer was all about where I'm at in my filmmaking career and where I see myself in the next 1-2 years. The RED was incredible, but coming up on mid 2017 everyone was owning a RED in LA and around the world. The RED became the new T2i, which is CRAZY. It got to the point where "I'm a DP and I own a RED" was a cliché. It was hard to stand out when pitching cause you and 40 other people under 25 had the exact same setup and were undercutting the competition. This was tough with my current client base because it was hard to pitch higher figures. In their eyes they saw a similar product for 3x cheaper and in the low budget market ($1,500-10,000) one of the objectives for them is to save money.
I stumbled upon Ryan Booth and Salomon Lighthelm and saw they were almost exclusively shooting on the Alexa--this interested me. They were producing some of the work I was interested in making and the images they were getting from this camera were just different.
I put this in the back of my head and kept creating with my RED. I was hanging out with my one of my friends Elliott Travis. "e trav" if you're a real one. He was telling me about the Alexa and how cheap they were to get and that I'd be projecting myself into a new market once I get one. They require more tools than the RED (Stedicam, tripod, dolly, etc), so so you have to get on decent shoots cause you can't really run without one.
I went on REDuser and saw one for sale 1.2 miles from my place in LA-- I knew it was a sign. I sold my RED and bought it just days after finding it. It couldn't have been a more perfect time.
MY THOUGHTS AFTER THE PURCHASE
After the 1,305,054 social media posts I finally turned on the camera and flew to Chicago and shot my first project on it, I fell in love. After that I shot 2 music videos, one of which was for Post Malone.
For me at least, the image just seemed more organic and not as sharp as the RED tends to be (which is totally fine, that just isn't my preference).
The camera also doesn't need to be broken down into 10+ pieces to make it work. It just needs a battery and the viewfinder attached and you are rolling, that's it. That to me was the golden ticket. No more screwing on battery plates, attaching top handles, screwing in side handles and putting on baseplates.
THIS ISN'T FOR EVERYONE AND THAT'S FINE
The camera itself weighs 20 pounds with no lenses or any battery attached--it's heavy. Luckily I have an easy rig and that makes shooting with this thing super easy. Maybe your style isn't like mine and you prefer gimbal moves and more flying around shots, that's totally fine. The Red + Ronin or Movi is probably a better options. Maybe you prefer something small and light for travel videos, the GH5 and A7S are probably more suitable options. Maybe you don't have the $$ for a RED or Arri, the Ursa Mini is probably your answer!
The point is, it's not just about the camera name or the image. It's the functionality and how you work with it. I love working with the Alexa and find it really easy to use. It makes me and my clients happy that I can move quickly and efficiently.
All in all, it's about your needs. Mine were that I wanted to stand out as a DP with something other than a RED, as well as get into the Arri market because I prefer the "look". This isn't the right or wrong answer, it's what works best for me. That's the only thing that should go through your head when making an investment in you and your brand.