Usually, the choice of defence against the English opening largely depends on what we play with Black against 1.d4 and, to a smaller degree, against 1.Nf3 and 1.e4. For example, a QGD player will seriously consider answering 1.c4 with 1…e6, while a Slav/Caro Kann one is likely to respond with 1…c6, etc.
However, Black can use a completely different logic when approaching the question: ”What to play against 1.c4?” We can choose an independent system with black pieces, almost regardless of what our repertoire is against the other first moves. And, in that case, the most natural reply to 1.c4 is 1…e5