Crowfield IS in Berkeley County but the High School is Stratford and is actually (practically) in Crowfield.
You can't do much better school wise than that without paying for it from my understanding. Nearby private high schools would be BE and Pinewood.
Foxborough is close to Crowfield and would also have your kids at Stratford. The homes in Crowfield seem larger but you can probably expect to pay a bit more (maybe). I live not far from there but don't let that sour your opinion too much
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I assume you want a military installation nearby for commissary purposes etc. There is one on the weapons station about 10-15 minutes (depending on traffic and your driving habits) down Red Bank Rd.
Depending on your budget, I'd look in Crowfield. It's a little (30 seconds or so) closer to school for the kids and the homes in some of the neighborhoods can be nicer (like the Hamlets).
I would steer clear of Sangaree.