I usually explore alone for several reasons. For one thing, I like to do a lot of light painting - particularly on more rural explores - which takes time and patience. Even if I'm exploring during the day, I would still be considered slow by most people's standards (I do it mostly for the pictures!), and I don't like feeling rushed or feeling like someone is having to wait on me.
That said, I have explored with one, two, three, or more - usually the person or persons that accompany me are in it for the same reasons I am (like the light painting for example), so it's not such a big deal to take our time. A partner makes light painting a million times easier than having to fumble around with technical and compositional shit while also manipulating the lighting around you.
The dynamics and overall experience feels dramatically different to me going solo vs going with a group, or even just one other person, but both options have been positive experiences for me overall. I'm usually more comfortable solo in rural settings and perhaps a little more comfortable with a partner or two in certain urban settings. Non-local urban settings are probably the times when I most want someone else with me.
It just depends.