Originally Posted by
sludgeogre
I was going to say save some money with the S2, but then you said you want midbass slam, and that's where the Horizon and the Tower really change things. The dedicated midrange driver is a dream. I listen to a lot of death metal, so midrange slam is what I crave, and the Sierra Towers and Horizon Center offer that in spades, so I think you should go with the Horizons.
Also, since you want to place them close to the wall, going with Horizons for L/R instead of the Towers or S2 is a great idea because they are front slot ported. You can put them very close to the wall and not lose any bass accuracy or midrange clarity.