I have a Prusa MK3 with the MMU2, and I definitely plan on upgrading at some point to the MK4 and MMU3. Since I don't have any direct experience with any multi-material options other than the MK3 with MMU2, the only thing I will say is to ensure that whatever you buy is an open source printer. I cannot tell you how much of a difference that makes when there are so many incredibly smart makers in the community that can take full advantage of that to provide solutions for basically any problem. My first printer was closed source, and I had a document that was several pages long that broke down everything that you needed to do (and not do) to get that machine working well and upgrade it yourself within the confines of what was possible. Prusa support is top notch, as is their quality. I can't recommend the brand enough, even if I don't have experience with the latest multi-material options.
3DPrinting
3DPrinting is a place where makers of all skill levels and walks of life can learn about and discuss 3D printing and development of 3D printed parts and devices.
The r/functionalprint community is now located at: or !functionalprint@fedia.io
There are CAD communities available at: !cad@lemmy.world or !freecad@lemmy.ml
Rules
-
No bigotry - including racism, sexism, ableism, homophobia, transphobia, or xenophobia. Code of Conduct.
-
Be respectful, especially when disagreeing. Everyone should feel welcome here.
-
No porn (NSFW prints are acceptable but must be marked NSFW)
-
No Ads / Spamming / Guerrilla Marketing
-
Do not create links to reddit
-
If you see an issue please flag it
-
No guns
-
No injury gore posts
If you need an easy way to host pictures, https://catbox.moe/ may be an option. Be ethical about what you post and donate if you are able or use this a lot. It is just an individual hosting content, not a company. The image embedding syntax for Lemmy is 
Moderation policy: Light, mostly invisible
My current printer is a MK3S+, and I love that Prusa is still pushing firmware updates for it. However, my personal experience with the machine has been pretty lackluster with multiple parts breaking and sub-par print quality. In fact, something else just broke yesterday (I have yet to diagnose exactly what) which is making me more eager to upgrade. I do wonder if I just got unlucky considering their reputation, but I can't say I'm rushing back to then with enthusiasm.
I do agree with your general point about open source. For that reason, the Prusa, Voron, and Ratrig are the most intriguing options. However, if one of the other two are likely to provide a better experience, I think it's silly to not even consider them.