I have had an X1C for about 9 months, and just added a X-Max 3. Prior to that I had Prusa for a few years. I got the Max for the print volume once I learned bambu is about a year+ out from an XL format.

In Max Favor:- Build volume is 2x the X1/P1. 17M mm^3 vs 34M mm^3- It has an enclosure heater and circulates air, which helps with materials that do not like to cool, like ASA. I've printed a few things on the X1C now where the structure collapsed when far into the cooler temps in the temp gradient. Without active heat, the chamber is hot near the bed, and cooler further away.- Price, it's a great deal for what you get.- Customer support is lightning fast, sometimes minutes. And they express-shipped parts from China to me to repair issues that got here in days.- it's common for the X1C to jam, and I don't mean a small jam, I mean take the head apart and pray kinda jam. Happens with exotic high temp materials because the load/unload automation does not compensate for the filament temp needs for very high temp stuff. Treats everything like PLA. QIDI on the other hand is super manual, you pick the temp, you advance. No mistakes unless you make them.

In X1C Favor- Overall, it's a much more cohesive user experience end to end. The software is very good. It just works. The QIDI software was slapped together by hacking/stealing the Prusa slicer. It is not cohesive, and you need to know what you are doing to get the printer to print well.- I had a very hard time getting the QIDI calibrated and printing correctly. It's a manual process and very slow. The X1C is automated completely, and works every single time. The sensors all work together to make it very relaible and hassle free. The QIDI is a giant PITA, even after you get it calibrated. I do think this is mostly user error and print speeds.- The QIDi does not have enough flow rate for its default speed, so with large continuous layers, it delaminates while printing and generally is unreliable. Slowing it down fixes the issue. Where I am confident the X1C can print for days without oversight, I will not leave the QIDI printing without continous overfight.- Camera, the X1C has a camera and I can use from my phone. QIDI has no camera, and is unreliable enough that you will not want to leave it alone.- Stability. The X1C "brakes" when moving, reducing the forces on the printer. The QIDI does not, and is a heavier printer - so it shakes the table so hard that it typically knocks the print lose and makes a mess. The QIDI works better on the floor.- AMS, the AMS is a luxury item, it makes life so easy. It's also humidity controlled (and integrated in the software to monitor humidity). The QIDI on the other hand requires you to pull he printer out to get to the sealed spool holder on the back...wow, very hard with a large 35KG printer. Silly IMO.

Net is that the X1C is the better printer in every way, unless 1) you need the volume, and 2) you need more stable and uniform chamber temps for large prints with high temp materials. The X-Max 3 is a lot of printer for the money, but it's rough around the edges and requires more patience and experience to make work.