Be carefully with LEDs. Some of them put out a very harsh light.
Sensibulbs are about the best you can get but are also very expensive.
As for brightness, it all really depends on what you use the boat for. You do not need much for daysailing. Living aboard will require a lot more. Find some fixtures you like with decent LEDs and install them. You can always add more.
Given how disruptive, and what a pain in the butt, it is to remove and reinstall the panels, I'm trying to get this as close to "right" as possible the first time. Also, given the cost of LED fixtures, I want to avoid "winging it" as much as possible.
I'm not, and will not be in the foreseeable future, a live-aboard. Here on the Great Lakes it's pretty much impossible to live aboard. So, my intention is to be able to light cabin when we return at night in the dark and find all the stuff that has rolled around the cabin sole.
I'd also like to be able to eat, cook, and read in the boat at night on weekend trips. My intent is to go to bed early on those trips, and get up early so I'm not blowing through amp hours. I don't need to perform surgery under the lights, just don't want to require a flashlight for any common activities when it gets dark.
The biggest thing I'm looking for is some kind of a guideline for lumens or watts per square foot I can use to make sure I'm within some margin of error on the lighting plan.