new playthrough character idea

It really depends on what you're interested in, and I don't mean gender in this regard. Both Josephine and Cassandra's romances are very traditionally "romantic." Cassandra's has you wooing her and composing a love poem; Josephine sees you fight a duel against a rival suitor. Iron Bull has the whole BDSM thing (you are the sub; you have no choice in this); depending on what you're looking for in a romance, this is hit or miss. Dorian's romance is a healing romance. Sera likes qunari, but she's only interested in women, as is Blackwall.

I would say that both Josephine and Dorian's romance are slightly more iffy for a non-human, and that is only because of the social constraints of nobility. They don't care, obviously, but if you're concerned with story, that might be something to consider. Cassandra eschews noble conventions, so I don't think that matters. There are no concerns regarding that with Iron Bull and in fact I think there is an interesting opportunity if you want to explore someone born to the Qun versus someone that was not, despite the fact that he can become Tal-Vashoth later on*.

* I can see this having some interesting dynamics depending on how you think of your character. If they were raised to think the Qun is horrid, etc, there might be some interesting internal conflicts there. On the other hand, if parents didn't talk about it very much, there might be curiosity, interest, etc, because the subject might have been taboo.