I just can't decide what to do.

I want to 3d print objects about 7" x 30" x 5" although I'd also like to print some things around 12" cubed but that isn't my main reason for building this . I was also thinking about using some Nylon X or similar nylon & carbon fiber filament. I have decided to go with an IDEX style dual print head.

Do I want to print the parts horizontally or do I want to print the parts vertically?

The vertical system will be far easier to build. I will only need one Z axis and the build plate will be much smaller, perhaps 12.5" x 15" based on some of the linear rails that I have and using IDEX dual extrusion.

The horizontal system would have a build plate of about 14" x 36" (with about 30" usable) and require two shorter Z axis and be more work to build and take up a much larger footprint.

I will be using good square type linear rails for the whole project.

I am concerned that printing the parts vertically will lead to less strong parts, although I think there may be ways to fix that and reinforce the parts afterwards.

I am concerned that printing the parts horizontally might lead to increased chances of peeling from the bed and other problems?

If it turns out that I don't need the soluble support material, the IDEX configuration will allow me to print two parts at once in either configuration.

Any advice is appreciated. I just can't decide what to do.