They are basically all the same academically (OFRS may score a tad higher in NJ ASK). BAC is the newest school and will have the most updated facilities (it's about 5 yrs old). OFRS is the oldest and smallest so will probably seem the "coziest". Flock/Koss are 2 separate buildings on the same campus - Koss is K-2, Flock is 3-5 so you will probably get the same "cozy" as OFRS.
All kids go to Long Valley Middle School for grades 6-8 and West Morris Central for HS.
Personally, find the house you like the most and whatever school it is zoned for is fine.