My advice is to have a look in mind first.
Determine the kind of looks you want then seek out various luts from different makers that fulfill it.
Then test. MANY luts even expensive paid ones can break images. They all look good at first, but can get you in trouble if you don't stress them hard before you use them.
It may take another year as films in production now using the camera won't be out of post until next year. The DXL is a great camera.
It's interesting to see so many ARRI camera's in the nomination. A lot of people are talking about camera specifications.
I think the main reason that ARRI both film and digital has influence is the operator centered design. Although they are starting to get more options, the camera has way fewer options than other cameras on market. It may sounds like problem but in effect it makes it easier to get consistent results and creates less potential for problems.
The colorspaces in the camera have 2 options and one log curve. There are a few viewing lut options, but none are so different that they cause a shot to be unusable if the wrong one is selected. The camera is designed to be rigged and has a great eco system of support gear. Menus are simple to navigate and easy as is reasonable for a cinema camera.
All cinema cameras are complicated but the ARRI feels just complicated enough for most shooting types. All of the other cameras have great strengths, but ARRI shoots straight down the center very well. If you need a 'generic movie camera' ARRI almost always fills the bill.
Where did you get the 36k of resolution for IMAX?
5 perf 65 is typically between 6k and 8k. 15perf is normally 12~13k
It depends on how much time you have in post. If you can dial in what you need in camera it is usually best.
It leaves the DP more in control of the look as different post houses will have different digital filters available. So if you liked a specific filter look, you may be out of luck or need to pay extra.
It also leaves more time in the DI for other work. Everything gotten right in camera gives you more time to focus on what wasn't right in camera.
Digital filters can be excellent, there are just some trade off's.