SleepDeprivedSloth
Out of the two, second option. You could do a compromise between the two and have an inner and outer harem though. The inner harem would have proper character development and a decent amount of screentime, while the outer harem are closer to background characters who will sometimes come up, but mostly exist to please the mc when the inner harem members are busy or he gets a sudden desire for something specific in the bedroom that his inner harem may not be interested in. Probably wouldn't develop the outer harem until the mc is stronger in this case though.
Hmm how about a compromise, make sure that all the beautiful and interesting women he came across to plough and also make sure that they have a semblance of characteristic to differentiate, while also making sure that they don't become a background character. 10 members seems low to me due to him getting stronger the more women he plough, so I think that a lot of women that are either strong or interesting like exotic beauty's.