Offshore wind farms are gradually being planned and built farther from the shore. The increased integration of wind power, also onshore, and the demand for improved power system operation give rise to a growing need for transnational power exchanges. Grid connection is a critical factor for successful large scale integration of offshore wind power. In this paper a comparison study between two different grid building strategies for offshore wind farms in the North Sea is presented for the 2030 medium wind scenario of the TradeWind project [1] (302 GW installed wind capacity). These two strategies are: i) A strategy based on radial wind farm connections to shore and point-to-point interconnections between countries, called radial grid; ii) A strategy based on the use of offshore nodes to build an HVDC offshore grid, called offshore grid. The comparison addresses different power system aspects, such as the total socio-economic benefit associated with each strategy, power exchanges between countries, offshore wind power utilization, grid congestions and utilization of HVDC cable capacity. We find that the offshore grid gives a total benefit over the economic lifetime of the grid for the European interconnected power system of 2.6 billion Euro compared with the radial grid. Our results show that even for moderate amounts of installed wind capacity, the offshore grid strategy is better than the radial one, assuming the future European power system will have a large penetration of offshore and onshore wind power.