Unless I know an opponent is unlikely to play it, I will usually play 1... Nf6 and transpose to the QGD. Then I may play the semi-Tarrasch or other QGD variations. I don't like closed openings, but like openings like the QGD which tend to lead to exchanges. Is that a reasonable approach?
Playing 1...Nf6 does not prevent White at all from playing the London System. If White plays 2.c4, it is is their choice to play the Queen's Gambit; not Black's decision.
Unless I know an opponent is unlikely to play it, I will usually play 1... Nf6 and transpose to the QGD. Then I may play the semi-Tarrasch or other QGD variations. I don't like closed openings, but like openings like the QGD which tend to lead to exchanges. Is that a reasonable approach?