I'm generally not opposed to it if there is a good storyline with a decent reason behind it but most of the time the harem is composed of the women the MC bumped into and got their hypergamy activated. I prefer stories where the MC forms real and deep relationships with people and that includes his love interests. Also, at a certain point there isn't any possibility that the MC can give a decent amount of love and attention to his wives if he collects too many. That's why, generally speaking, I'm not against two... maybe three but anything more than that starts to annoy me.
What I love the best is to see an MC have a wife (or a small harem) where the women have a great relationship with both each other and the MC. Additionally, I love it when the MC shuts down shallow women who other authors would probably have included into the MC's harem simply due to them being an attractive women who casually exists nearby to the MC.
