Do you have a big budget to buy parts? You can do work in CAD? Copy the Pantheon HS3 design approch. Always question design decisions. In the broader picture of 3D-printer is the HS3 still engineering porn: https://www.youtube.com/watch?v=ooE0Xc6jPBY
I can make reliable and accurate.
I’m thinking a core XY
Mark my words: CoreXY hype is slowing down. In the next years, we will see people avoiding it due to the accuracy challenge of long belts. Not sure what will be the next trend but maybe we are going back to shorter, separate belts with the motor riding on the gantry once more. I don’t see ballscrews happening soon as all of the china, low cost, easy to source options are unsuitable at the moment (wrong pitch/mm per revolution).
With Prusa publicly talking about E3D Revo issues (and implementing a special slicer mode for them) we might see there too a new design.
The benefit of core XY is that you don’t have a heavy motor riding on the X-axis allowing you to push higher speeds without increasing the rigidity of the y-axis. The downside is the long belt which will stretch a tiny bit meaning a lower accuracy.
With core XZ you don’t gain anything as the z-axis is generally not high dynamic meaning the weight doesn’t matter at all but still need to eat the downside of a long belt. In my opinion, it is just a stupid gimmick people fell for because is looks novel or cool.
Also core XZ is a bed slinger. With small objects, this is not an issue. The higher they are and the less rigid the print is the bigger the issue of the 3D print itself deflecting gets. With the usual 20cm height and the usual helmet and the like this aspect doesn’t matter at all.