Depends on your personality. I started in a single-man cell for the first few months, then I was in the Hole for a couple of stretches and that was solitary, and then during COVID I got my own cell again for about 8 months. I am an only child, so I am incredibly comfortable being alone for long periods. I hate sharing a cell with someone else, as 99% of the time you probably won't like the other person. Most two-man cells only have enough floor space for one person to stand, so you are constantly shuffling around each other. And bumping into anyone in jail is immediate grounds for a fight, so you are constantly on guard.
Plus, no-one wants to be in the same box as another man who is taking a shit. And the food is so bad that practically everyone has diarrhea all day every day.
Of all the things you see on TV and in the movies about prison, the worst two are not shown: total mind-numbing boredom, and your cellmate's farts.