Well, it looks like I have a different mindset then.
I'm a fan (and just a fan now, if we're going by those descriptions above) and I won't hesitate in saying that I don't like all of the members equally.
All right, that was worded poorly. My bad. What I mean is that I don't dislike, and won't put down, anyone in BTS because they all have their worth and purpose in the group. I simply favor some more than others. I have some number of biases in the group, and the number is less than seven. It's been like this even back when I was more into the fandom.
I get that they all have their unique charms (not listing everyone or all of their positive traits, but for example, RM with his leadership and being the working bridge between the group and U.S. market, J-Hope for his top-notch dancing and bright energy, Jin for his variety sense and visuals that draw in outsiders and plus he always has the best solo songs in the group, etc), but some of these charms are going to appeal to me more than others. It's unlikely that we're going to like every kind of person, every kind of personality out there at the same level anyways.
Anyways, you can add my account to your ignore/foe list now because I'm a "solo stan." You have my permission.
On the topic of their respective popularity/fanbases, I do think that J-Hope's individual fanbase is the smallest, but it should be growing because he's been able to really showcase himself recently through his mixtape and the entire LY era. Also, I interact with a group of people on another site, and I want to say that most of the BTS fans there are J-Hope stans (or at least the most vocal ones).