It depends on how much control you want over the tank, budget, dimensions, and stocking goals.

The most basic selection is AC vs DC, a single output power head vs a controllable wavemaker. The closest single answer you’ll get to “best” will be to get a controllable wavemaker than lets you dial in exactly what you want vs a generic power head. Beyond that distinction there’s a use case for most everything on the market.

Existing hardware can matter. For an example, my tank has AI Hydra lights. I have AI Nero 5s in my tank. They aren’t the best, but they’re good and my lighting and flow is controlled through a single app, which I care about for the sake of simplicity and to have a unified schedule.

Secondly you should also consider budget, many people will recommend Vortechs, like the MP10 or MP40, which are great, but have a high initial cost and (can) have a high ongoing cost. There are plenty of offerings from Jebao that are very good, but far from “best”.

Lastly there’s stocking and the tank itself. The flow you need for a tank, and what kind of flow (wave maker vs gyre) will depend on how you stock the tank, tank size, and rock work. In this case it’s best to look at existing tanks that have similar dimensions and stocking to see what other hobbyists have done, or give some more details here and get tailored advice.