'Best' has a number of definitions. You can set up an op to make the max weight per square foot of floorspace or you can set one up that is deadly easy to use but still makes good output for effort expended. It's hard to get it all in one type of watering system.
The most productive watering systems are aero & DWC because of the lack of media and constant access of oxygenated nutes to the roots. They're also the most fiddly as they are dependent on air or water pumps to support the plants.
In DWC, an air pump/power failure lasting more than a few hours is a big problem. Roots are submerged and will drown without a constant air supply. Some sort of battery backup for air pumps (a computer UPS will do) is a really good idea for DWC. Spare pumps on the shelf are smart, too.
Aero systems which generate a spray by pumping water through a nozzle can clog and need to be checked frequently. Aero systems which make mist with an airstone in the bottom of a tank of nutes with the roots above the waterline (basically DWC with a low water level) are a bit more relaible.
Flood systems with plants in pots stuffed with a medium are dead easy to set up and run. Different media are more or less absorbent. Pellets hold almost no water, rockwool holds almost too much. In case of a pump failure, there's a water supply in the absorbent medium. The amount of fail-safe time depends on the size of the pot and type of medium. Plants in pots are also easily movable within the op for maintenance or putting slowies in better lighting positions.
Floods which use pots of pellets will have the least amount of reserve water but can be flooded most often, allowing best access of oxygenated nutes to the roots. Mature plants in pots of pellets can be flooded 5x/day, more or less, depending on the size of the plant at the time. These systems rival DWC & aero in productivity. However, the pellets are heavy and can be a disposal problem. Double bagging is a very good idea so they don't split when being put in the rubbish truck. Can be a bad look... You can clean/sterilise and re-use pellets but it's a prick of a job. Failure to totally sterilise pellets can lead to transfer of root diseases on to the next crop. The pellets will eventually accumulate nute salts and have to be discarded.
I use flood systems and prefer pots stuffed with lightweight disposable media- no cleaning, always sterile for every batch. I used to use pots stuffed fully with rockwool floc. However, RW floc holds so much water that it's only possible to water 1x/day, more will cause root problems.
I now tightly pack about 25-50mm of floc in the bottom of each pot and fill the rest with
Fytocell, a resin polymer foam-based medium. Fytocell is 40% air, nearly impossible to overwater and can be flooded much more often than plain pots of floc. However, the Fytocell foam is crumbled and tends to escape pot drain holes. The high air content means pots of it will float. The layer of rockwool allows water to go in & out of the pot but keeps the Fytocell from falling out and also weights down the pots enough that they will not float. I flood my larger plants in Fytocell 3x/day.
Flood systems are mechanically very simple and can not clog with nute salts. They're not the very top producer but not far from it. However, they
are the slacker's choice for ease of setup and routine operation. I have 96 plants in flower all the time. I can't imagine the maintenance of a 96 plant DWC!
If you're an enthusiast and like to fritter about in your grow, you might be OK with DWC or aero.
Setup costs for really small ops (<20 plants) of either type are comparable, but the larger the plant count, the cheaper comparable capacity flood systems are to set up.
