I think my hopes for DA3 as far as romance is concerned have more to do with the characters themselves rather than their sexual orientation and whether you get a sex scene or not (although I do miss the option to kiss or sleep with your LI whenever you wanted in Origins!).
In the previous two games, they tended to emphasize particular romances, Morrigan and Alistair for Origins and Isabela and Anders for DA2 (from what I could tell). Morrigan and Isabela were used in the main advertising campaigns, and all four have more importance (and at times were even pivotal) to the main story than the others (Zevran, Leliana, Fenris, and Merrill).
So, these romance options appear to be the "canon" options- the ones that fit the story most and the ones you seem more drawn to pick initially.
I want romance option that are all equally important to the main storyline of DA3. I want them each to receive equal amounts of character depth, attention, but not to sacrifice the quality of those characters or their stories. I want the romantic scenes you do get (be it a kiss, a love scene, a cuddle or a hug) to be emotionally satisfying and well written.
If I had to go for specifics, I want romances who are polarized in personality, but not necessarily in opinions of mages vs templars, for example. This is part of why Fenris, Merrill and Anders annoyed me, as much as I liked them over Isabela. They were both so polarized. But with Isabela it didn't matter what side you're on. If we're going for the usual four options, I think they should have one male and one female who are both neutral.
Someone with Aveline or Varric's personality would really appeal to me.
I also noticed that in Origins it was a mage, a warrior, and two rogues, and then a warrior, a rogue, and two mages in DA2. Just for pattern's sake, I would like to see a mage, a rogue, and two warriors.
I think that about sums it up for me.