1. Choices & Consequences
What is most important to me is that I can actually see my Choices respected and reflected in the World. These don't have to (and actually should betetr not be) great,, world-changing Events, but something more little and nuanced as the simple Way you talked to a Person influencing their Opinion of you their reactions to your Actions. The Devil is in the Details, but those especially, often feel like little Nuggets you can find. Hide important Decisions behind small Things, like the second Hardening of Leliana in Inquisition. And if there's a world-changing Decisions, have it change the World dramatically. I want to see my Influence, how I changed the World.
2. Characters & Relationships
And by Relationships I don't mean exclusively Romances. Characters have always been BioWare's strong Point, but it should be reiterated that they should stick to their Strengths. Have the Characters be deeply integrated with the Plot of the Game, have each of them be an Influence on the Plot, have each of them fill important Roles that aren't just felt in the final Missions. Have their Stance and Relation with the main Character mean something and offer up more Distinctions between "Indifferent / Friend" and "In Love". Offer up more Dialogue with each of them and don't ever build up Calibration Walls again. Have them reflect on the World and have the World reflect on them.
3. The overall Story
Now, this could be positioned higher, but the previous BioWare Titles have shown that with great Characters even a mediocre overall Story can be made great. However, ideally, both should be enticing and create a greater Whole. There are some Steps to make it easier and the first and most important Step is to make this Story a more personal, intimate one. Don't offer up more than one or two World-changing Choices per Game and instead have this Story reflect more on the Characters and their Relationships with the People they can influence. In a Way, I would say, they should try and go back to many of the initial Story Ideas for Dragon Age 2, as that Game had many valuable Approaches, that unfortunately got swept under the Rug with a rushed Development.
4. Player Agency
Going Hand in Hand with a more personal Story would be the definitive Need for allowing more Agency to the Player Character. I recognize that this is not as important and depends greatly on the overall Arc of the Story, which is why it's ranked at this Point. However, if possible, I think it would be greatly appreciated if the Player was able to flesh out the Motivations and Personality of their Character and be provided with Dialogue Options in Accordance to that. The important Thing here is to allow the Player to define, why the Character is what they're doing and allow them to be consistent in the Characterizations provided to them. Do not let the Character go through mandatory Changes or out of Character Moments all too often.
5. Exploration
This is a no Brainer and not as important as most People think it is. I am a fan of Exploration and fully explored all Maps in DA:I (I'm insane, I know that), but only if it is not a Detriment to Story and the pacing of the Story. However, it is still very much a Focus of the Game, so make it as important as it can be without drawing the Story out or becoming meaningless. Provide the Player with more Reason than "gain Power" to go out into the World, maybe have it change somewhat drastically due to Player Actions that might or might not be related. Do not let the explorable World be passive, but have it react to the Player. This would fuel their Incentive to explore again, as they want to know how the World changed at their Whim.
6. Not too cynical
I got everything I deem most important for anyone out of the Way, so this is mostly my personal Agenda. I hate that Stories in the last few Years have been confusing Cynicism and Darkness with Realism. The World isn't that Way. There is as much Good as there is Bad in the World. And I thought, in a Way, Mass Effect has done this right already, seeing as Paragon Choices had far less negative Consequences than Renegade Choices. Your Trust and Idealism was more often rewarded than punished and while I think, for Fairness, it should be somewhat 50:50, I felt that the underlying Message there was quite uplifting. And I want to be uplifted when playing a Game. I don't care if my "good" or better, "idealistic" Choices maybe make the Gameplay harder (which I think could be an interesting Mechanic), if I worked hard for a good Outcome, I just feel that much better afterwards.
7. Integrated Gameplay
Every Bullet Point above was essentially concerning the Story and it's Presentation, and not without Reason, as this is where a BioWare Game rises and falls. Gameplay is of course, a Concern that should be adressed and while I could repeat the typical Arguments that were mentioned before, I'd like to go into my Idea from #6, where smaller Choices could often affect Gameplay. For Example, take the Elnora Choice from ME2. I think, a better Handling of that Choice would have been, if she didn't just vanish, but that letting her go might have made the Mission harder in Gameplay Terms. I would like some Penalties of my smaller Choices, especially the more idealistic Ones, be reflected in Gameplay. Might as well serve as a small Distinctions: Pragmatic Choices ease up your Gameplay, Idealistic Choices make it harder. I'd like this kind of Integration between Story and Game.