The EPC is one of the many conservative breakoffs from the PCUSA. The PCA is as well. However the PCA holds strictly to Westminster. The EPC has defined a few essentials, and allows more variation. They allow congregations to ordain women, which the PCA does not.
Note that congregations in both the PCUSA and EPC are likely to vary. There are conservative PCUSA congregations, even in the Northeast. There is no mandate to marry gays, although the national leadership thinks it's appropriate. You might well find a PCUSA congregation that's OK. PCA churches are likely to be more uniform in belief, though not necessarily in the "feel" of the congregation. So the best advice is to try congregations near you and see what they're like.
If homosexuality is the key issue for you, note that RCA congregations have varying views. There have been gay marriages and there are gay clergy within the RCA, though not necessarily in your region.
The CRC prohibits gay marriage, but in the most recent study, the majority report recommended softening the position. The minority report was adopted, but you've got to wonder how long a denomination will continue to support the advice of a minority of its leadership.
If homosexuality is the most important thing for you, I think the PCA may be the only safe place in the long run, though for the moment the conservative offshoots such as EPC and PCA all take the traditional position. However if you're OK with a church or even a presbytery / classis that you agree with, you should check all the local churches from Reformed denominations.
