What size wire would you use for a new 200 amp direct burial service?

This is a voltage drop question. A 300 MCM copper or a 500 MCM aluminium conductor will limit the voltage drop to 3% or less when supplying 200 amps for 450 feet on a 240 volt system. The cheapest of the two conductors would be the aluminium conductor. For direct burial is will have a ACWU 90 designation.