Actually, my main sentai comparison is the hard focus on other Riders for their episodes. Generally, with a smaller number of Riders, the show is like 70% main Rider, and the rest the occasional focus on the others and villains. Whereas Sentai operates on the character focus rotation: Setup > Red > Blue > Color #3 > Color #4 > Color #5 > New Situation > New Ranger > Rotate Again. It's about the ensemble.
Saber operates similarly so far, because they have so many Riders. Episodes: Saber > Blades > Buster > Espada > Kenzan > Arthur Robot > Slash > Calibur Reveal (New Situation) and now we're rotating again.
Now look at another huge multi-Rider show, Gaim. The focus of each episode: For the first 10: Gaim, Gaim, Baron, Ryugen, Gaim, Bravo, Gaim, Baron, PLOT SHIT focused on Gaim.
I think in the rush to introduce so many Riders, and the switch in writers, Touma gets the short end. He doesn't really feel like the focus of the show, the main character. He is Saber, but he partially just feels like that guy who happens to be around and needs to be in every episode (see Kyuranger's Red as an example). I honestly don't get a strong feeling of character impact from Touma, because the show isn't really focused on his conflicts, emotional or external. If anything, despite his uneven writing, Kento is probably the most meaningful character.
Now add in the main opening and ending focus on 5-6 Riders of various primary colors *and* the dancing ending, and yeah, and the sentai comparision really shouldn't surprise you.
EDIT: And like, I don't hate Saber. It's better than Ghost, for example. It just feel like they're going "RIDERS, RIDERS, RIDERS, FIGHTS GALORE" and then they look back and realize they have to tell a story and add characterization after the fact. And it's storytelling weaknesses are compounded when its airing next to Kirameiger and Ultraman Z.
