There isn't really a best, just lots of opinions....
FYI, lights up there will reflect off the bonnet and wings, so aren't very good for driving about with when on. But they can work well for static lighting or work lights.
As for wiring, it really depends how you want to use them and where you want a switch. Ultimately you need to get power up to them, so you'll either need to run a wire down the windscreen, rear or somewhere, drill a hole or maybe feed though a door or panel/roof seal.
Halogen lights will need quite a bit of current, so make sure you run via a relay and use suitable grade wire and connectors. KC offer a number of lights and lenses, I think they are often quite a spot beam, so you may want all four to give a wide enough illuminated area.
If you plan on fitting other powered items (lights or other) to the roof or rack, you might want to wire with consideration for expanding to other items.