Academically - any of the 3 would be a good choice. Community wise each offers a very different environment - F&M is in the heart of Amish country and Lancaster is "a bit" of a city... Gettysburg, well let's just say it's a tourist destination - loved the small town feel there just off-campus... Hard to complain about playing all your home games on campus right next to one of the main battlefields. Dickinson is in a small community Carlisle and has a larger school footprint. IIRC, there is train service - it's about 45m west of Harrisburg. I think DC had a very beautiful campus - my favorite of the Centennial Conference schools I visited with my sons (one went through the football recruiting). For any of them it's a matter of personal preference which is why it's so important to do those visits and get to know what you want.
Baseball wise, GC is usually competitive every year - the HC has been there for quite a while. F&M and DC have gone through ups and downs. In recent history I think F&M has been better, but still let's face it - you're going to a D3 academic school - are you there for baseball or school (and at $50K+ per year)... When we visited DC (in early October) HC he wasn't in full recruiting mode yet, but was very honest and open about his process. I think my son had already mostly made up his mind (Muhlenberg) though and didn't really want to wait. We never visited GC, but they did seem to come to a lot of the Top96 events and were looking for specific things.