Well, I prefer shooting armies, but if I wanted an assault unit I'd use Incubi. The thing for me is that they bring good WS, a decent number of attacks, an actual armour save and S4, AP2 weapons in combat.
Conversely, Bloodbrides just don't seem that good. They get an extra special weapon (meh), and an extra attack, but this is undermined by them being S3, and WS4. They still feel like a tarpit unit, instead of a damaging unit and, that being the case, I'd rather just use normal wyches - which are both cheaper and scoring. I guess they get a little better with drugs, but so do troop-wyches, and I'd take cheaper, scoring units any day.
Basically, I just don't see bloodbrides accomplishing much that couldn't also be done with either wyches or simply with shooting. On the other hand, since our AP2 weapons are often busy with vehicles, Incubi can bring a decent amount of anti-infantry AP2 weapons to the table.