Its a bit like asking "what kind of batteries
should I buy?"...or boat
..., with no more data. Cant provide an accurate answer without more info. Sooner or later you will need to answer the basic questions...or wish you had.
In lieu of basic data, two popular options are Spectra and Cruise
Spectra is very efficient 12V driven. That efficiency comes at a hefty price
RO is AC driven and comes at a much lower price
Both are good systems...for the right application...whatever that is...
Each has a range of output capacities to meet your needs...once you define them.
We are fortunate to have two active memebers here who represent each of the above: Tellie and Rich respectively. Both share their knowledge and perspectives very generously. They are gonna ask you the same questions I did.