Do you play better alone or does it not actually matter. I've had sessions where someone sitting next to me completely threw me off and others where it made no difference at all. Not sure what that says about me.
Alone every time. the moment someone is watching I start making decisions I wouldn't normally make and I can't tell if it's performance or just nerves.
Alone without question, having someone around who doesn't gamble is the worst because they start asking questions mid spin and the questions are always at the exact wrong moment.
my girlfriend watches me sometimes and I genuinely play worse, not because of her specifically just the awareness of being observed makes me second guess everything I'd normally do automatically.
I actually play better with a friend around, having someone to talk through a session with keeps me from making stupid impulsive decisions, the social element slows me down in a good way.
alone, always, it's not even a preference it's just how I've always done it and the idea of someone watching feels genuinely uncomfortable for reasons I can't fully explain.