One Big Power Supply vs Multiple Smaller Ones
I'd go for many smaller ones.


Cheaper.
Quieter (no fans)
Cheaper to replace in case of failure (you just replace one instead of all of them)
Better control over voltage drop (you can put each PSU closer to the load to extend efficient mains wires and shorten inefficient 12V wires)
Better control over cooling (you can put them farther apart to disperse heat production)
Ability to shut down (disconnect from mains) parts of the system to increase efficiency (underloaded PSUs are very inefficient)


Single large PSU is unavoidable for single large load - that's why they're more expensive.

As a side note, I am bit concerned about the "behind cabinets" part. A 240W PSU running at 80% efficiency will dissipate almost 50W on it's own - that requires pretty good access to fresh air. No problem if they are between cabinet and a wall and this space is open at the top and the bottom - they will create enough draft on their own. But if you close the space, they'll cook themselves, greatly shortening lifespan.