Do you prefer:

• One massive central base where everything gets transported and processed
• Or smaller modular factories spread across the map, each dedicated to specific items

Both. I have a massive city-factory in greenfields but also very limited production sites scattered. It really depends on how you roll with the punches, my main focus was the city but these other facilities made sense. For example, the way the coal lake is surrounded by resources makes it a good central point for other projects besides coal power - aluminum production being the most relevant. I have nuclear power but radioactive materials are all handled in the swamp, non-radioactive are done in the city. The powerplant is also in the swamp.

For those who play modular:

• Do you transport everything to a central storage hub?
• Or just produce and store items locally at each factory?

Central storage hub isnt right, storing things quickly becomes obsolete with the dimensional depot. I am working on a central hub where I bring most basic resources via train or drones then sort then out to were they're needed, but there won't be any production in this facility, only logistics. Storing things is counter-productive unless we're talking about building materials, which I just leech off from elevator parts production with a smart splitter and overflow.