I try to look at the SP+ at more of a "30,000" foot view than worrying about whos #1 vs #2, etc. I see a few tiers in there.
Tier One: Bama, OSU Clemson, and Georgia. Don't think anyone can argue that in one way or another, these are your favorites. Georgia maybe a hair behind the other three, but enough ahead of the next tier to keep them out of Tier two. All capable of 12-0 or 11-1 regular season records.
Tier Two: PSU, LSU, Florida, OU, Wisky, A&M, Auburn. All very good teams, All more likely in the 11-1 to 9-3 range. I think Florida is the team that is most likely of the group to outperform their peers. Not buying A&M until they can knock off at least one of the Tier One or Two teams they play (Bama, LSU, Auburn). They finish with Bama and LSU though so they be flying high before then with Auburn as the only probable loss up to that point. I think Wisconsin is most likely to end up in the Tier Three by seasons end.
Tier Three: Notre Dame, Oregon, Texas, USC, Michigan, North Carolina. This is the strangest group I think. Lots of traditional powers that have underperformed thier "status" in the last decade, along with some newer blood. A win over any of these would obviously be considered a high quality win by seasons end. 10-2 is probably the ceiling for these teams, possibly 8-4 or 7-5 if things really slip. I think Oregon and Notre Dame are the most likely to outperform expectations in this group.
Tier Four: UCF, Tennesse, Minnesota, Ok St, Memphis, Miami-FL, Washington, Nebraska. This essentially rounds out the Top 25. Solid teams, but I definitely see the SP+ predicting an improved season compared to last year for a lot of these teams (UT, Miami, Nebraska). Minnesota finished higher than this tier last season, but SP+ is not one to overreact to one year surges (or declines). I could see them the most likely team here to break into a higher tier.