Why won't you consider augmenting with subwoofer? Even a tower speaker with built-in powered subwoofer can't do what monitors plus subs can do. There's far lower cabinet resonance in a monitor and it's easier to place bass generators where they work well with the room while placing the monitors where they image the best.
You could, for example, get a pair of KEF LS50s, which are class A sound down to around 60 Hz, and have the rest picked up by a good, fast sub or two.
You could, for example, get a pair of KEF LS50s, which are class A sound down to around 60 Hz, and have the rest picked up by a good, fast sub or two.