Trogir to Dubrovnik - Bus or Ferry?

There are more bus services than ferries each day and they take about the same time, so I would go by bus.

My personal preference would probably be a ferry. I have actually done this journey half by fast catamaran and half by bus (stopped for a few nights in Korcula in between). I hate being stuck in a tiny bus seat for hours. On the other hand, the catamaran was a bit bumpy too - I could get up and walk but it was not always easy. If it was a conventional ferry where you can sit up on top in nice weather, I would take the ferry hands-down, if the travel time was even close to the same.

But...some people don't mind a bus, and it might be more practical in some cases. Although it was years ago, when I got the bus to Korcula from Dubrovnik, I first had to take a local bus from the old town to the main bus station. Not sure you'd have the same issue with the ferry - maybe.

I would always opt for a ferry over the bus. Not as confining.

Ferry unless the timing is terrible. Bus takes just as long and you aren't free to move around. On the ferry you can go to the bathroom, get snacks and coffee, much more enjoyable.