East St. Louis seems to be the clear pick for the Southwestern Conference. Edwardsville brings back several key players, so I would not count them totally out of that race.
The MVC is much more interesting. Last year's top four teams(Highland, Triad, Waterloo, and Mascoutah) all started a senior quarterback last fall.
Highland won last year's MVC title with a 5-0 record and reached a running clock in four of those games. But that Bulldog team was senior heavy, so this will be a very different team.
Triad went 4-1 in conference play and 7-3 overall. The big question for the Knights is how will they fare in the wake of their head coach of 20+ years stepping down.
Mascoutah finished fourth place in the conference last year, but they also knocked Highland out of the postseason in a remarkable upset. The Indians top 8 tacklers last year were seniors and 50 of their 58 touchdowns were scored by seniors as well. They do benefit from making last year's top three conference finishers come to Mascoutah, where they have proven much tougher to beat.
Waterloo hit seven wins last fall last year for the first time in 20 years, which saw them take third in the MVC and nearly taking down eventual state-champs SHG. The Bulldogs have a tough start to their schedule with three strong non-conference opponents before taking on Triad and Highland to open MVC play, which is challenging for a team that heavily relied on a few seniors.
Jersey and Civic Memorial are coming off losing seasons and I would be surprised if either puts themselves into the title conversation this fall.
If I had to pick a winner, I would say it comes down to a split between some combination of Mascoutah/Triad/Highland. 2018 Highland was the last MVC team to go a whole season undefeated against conference opponents, so precedent supports this.