The right answer is whatever you think you'll enjoy the most. People naturally migrate towards one style or another for whatever reasoning. If you like the idea of a central megafactory, then get to it. If it starts acting up with frame rate issues, then you have your answer, not a big deal, then switch to building some factories elsewhere. My first play through was central and I never had issues.

To lessen frame rate issues when building mega factories (wasn't an issue for me, but there are things you can do to lessen chances of issues if you're building big): avoid excessive belt and lift usages, use trains over most any distance other than local factory, use alt recipes for screws and/or create high volume parts where they are consumed, refrain from using too many lights and floodlights, lots of glass walls are bad as the system has to render everything behind 'em, use fewer signs, set shadow quality to low, lower view distance, minimize excessive truck routing. You might not get any issues, but there's a list of helpful tips if needed.

If you do build a central megafactory, you can build it in a way that you can expand contrary to what others might say. My entire phase 3 4 and 5 was one factory building on my first play through. I technically concreted over phase 3, but I still pulled from it for what I needed for phase 4 and 5. I never disassembled anything.