My personal favorite is the Eastern. My children are now a little older, but this was the easiest for us. The ports were VERY friendly. We did the Western 2x, but felt we enjoyed the ports of call more on the Eastern. We did our own beach excursions in St. Thomas and St. Maartan, and never had a concern..
It is all personal preference of course, and I would cruise any route that I could, on the week that I could.
I have never done the 3 or 4 nighter (yet) as I feel 7 was too short on the ship.