10 isn't enough for an all time list unless you split it by classification. Shelbyville would almost have to be #1 for the incredible run decades ago, and even though they have fallen on hard times for a while now if you say "all time", their consistency and dominance back then may never be repeated. Several smaller schools have impressive resume's for streaks and /or consistent winning at high levels, such as Bradford, Gleason, Wayne County, Jackson County, Clarkrange, Cloudland, and some formerly larger schools that have dropped including Gibson County and Westview as Pioneer mentioned. More who have been noticeable as above average, some in streaks and some always hanging around as district, region, and sub-state teams include Scotts Hill, Lake County, Union City, Middleton, Pickett County, Celina.
Not as familiar with the larger schools, but Blackman and Riverdale have been formidable in the past, and you for sure can't leave out Bradley.