I consider tournaments as a big factor, so here's my list. Oh yeah, I added their record against teams included in this list (only regular season or tournament games)!

Rank) Class Team, Record, Tournaments, vs. Top 15
1) 4A Irmo, 15-0-0, 3-0-0, 4-0-0
2) 2A Bishop England, 14-1-0, 6-1-0, 4-0-0
3) 4A Ridge View, 12-4-0, 6-1-0, 3-3-0
4) 3A Riverside, 11-2-4, 2-1-4, 1-1-3
5) 4A Dorman, 14-2-1, 4-2-1, 1-2-0
6) 2A Chapin, 11-0-0, 3-0-0, 1-0-0
7) 4A Wando, 14-2-1, 2-1-1, 1-1-1
8) 4A Aiken, 12-3-0, 2-1-0, 0-3-0
9) 4A Sumter, 12-3-1, 3-0-1, 3-1-1
10) 3A Brookland-Cayce, 12-4-4, 3-1-4, 1-2-2
11) 3A Greenville, 10-1-0, 0-0-0, 1-1-0
12) 4A Summerville, 15-4-2, 3-3-2, 1-3-0
13) 4A James Island, 13-5-1, 4-3-1, 1-4-1
14) 3A Myrtle Beach, 13-2-0, 2-1-0, 0-1-0
15) 3A D.W. Daniel, 12-1-0, 0-0-0, 0-1-0