Like all things cable related, it's very subjective and the only opinion that matters in the end is yours. I have bi-wired my speakers mostly because they have the posts for it and so I ordered that style of cable to start with. A well terminated 12 gauge cable should work great, 14 probably works well too.

With hearing loss I'd suggest looking at investments to lower the noise floor of your room. That can be as simple as sealing a door with some felt pads or weatherstripping or as complex as some acoustic panels. Lots of smaller tweaks have made a big difference in the sound of my room like moving the speakers around, using different feet, carpet spikes or isolation pads.