So option b is cheaper, simpler(no panel's installation) and without any aesthetic impact.
There must be some drawbacks though. I have no clues on the advantages of each solution.
The important drawback is, that the acoustics cannot be improved with RoomEQ.
Professionally sounding systems (as differently as they are sounding), have one characteristic in common, which everyone immedialy notices, without knowing the reason: the controlled/low amount of indirect sound and the high amount of direct sound.
IME a professional sound starts to manifest, if RT60 reaches indeed 300 ms or below (for typical room sizes) and Clarity 50 reaches 15 dB for the midrange.
Does reverb time really play such a big role?
Contrary to acoustic concerts, where one single concert hall for all instruments is part of the whole "mix", any other kind of recorded music or audio, uses (very) different spaces and ambiences and amounts of it, for different instruments/sounds. The amount of the sound always created by the listening room, must be adequately low, that we are able to start to hear the ambiences in the mix, and not a reverberated mess imposed on everything.
It does not matter which RoomEQ, how expensive speakers and subs are, the room will continue forever to superimpose the huge amount of his own sound on everything, if it is not reduced. Even if you would spend a million dollars, the room will stay as loud and do his mess, as he is doing now.
RoomEQ cannot reduce the level the room is imposing on the mix and therefore cannot create that professional sound and vibe acoustically controlled setups have in common.
Ofcourse marketing can do a lot. And imagination of customers, who do not want to hear reality, is a strong force.
Filling up dips:
At higher frequencies with EQ can work very well, but certain cancellations cannot be overcome, because you know zero multiplied with any bigger number (frequency level increased by EQ) is still zero.
And be warned: if you look only at the SPL graph and ignore the time domain (the behaviour over time), filling up dips may look much flatter, but may sound worse, because the SPL is showing the energy over the whole time, not when it arrives. It may arrive at a later time, or create a strange kind of pressure in the ears.
You can use a (pulsed) sine wave of the problematic frequency you filled up and listen, how it really sounds, after filling up dips. You may not like it, despite a flatter SPL measurement.