The power of the Queen's Gambit is beyond question, even though it allows some serious defences - the Slav and Semi-Slav are favoured by the elite. Kasparov was playing the Queen's Gambit Accepted until he retired, and the Queen's Gambit Declined has been trusted for a century. The principled way for White to build a repertoire after 1.d4 d5 2.c4 is to play the critical main lines. Take as much space as possible - no compromises. The Tarrasch, Chigorin, Albin and all minor lines are also met with the same vigour - this is a complete White repertoire after 1.d4 d5 2.c4.