Saejima takes a bit of getting used to (fighting-wise), but I LOVE his style and it's a great style for crowd control.
Tanimura is all about reversals and counters, with a bit of kicking; he's flashy, but I don't like a single thread of that character's existence.
When it comes to actual characterization and their role in the plot, Saejima is done flawlessly, IMO, easily the best plot in the entire game (even if a bit farfetched, at the very least his character comes out as a shining star). Tanimura, OTOH, is shoehorned to basically be the main protagonist and, like Sayama, is a whiny little baby (but he doesn't cry at least).