What are your main selling points for ME: Andromeda?

1)Characters. BioWare does the best virtual characters. They did the best companion ever - Mako in SW:TOR (nothing comes even close).
2)Main Plotline. They are also great at telling stories. Sometimes they don't know how to properly end them, but that's entirely different story.
3)Multiplayer. People that spent hundreds, even thousands, of hours playing ME3MP, raging at that troll RNG store, wondering about mental health of pugs, doing platinum solos (or duos) using various very suboptimal gear and many other extremely fun things know why.

Now we just have to pray to Big Green Pen, or whatever Celestial Entity you believe in, for BioWare not to fuck things up.

Always tough to narrow to 3 when there are so many options but I went with Story: Main Plot, Story: Characters, and Gameplay: Combat since those 3 represent the majority of the game. Still, if Bio is going to cram exploration down our throats then Gameplay: Exploration and Story: Sidequests needs to be right up there in importance lest we end up with the same flaws as DAI.

I would consider all of them to be honest. Since you asked for only 3, I picked Gameplay: Exploration, Story: Main Plotline and Romances. Space exploration in the trilogy was never done well so I'm hoping for an open world experience where we can go to any planet(s) whenever we want without any limitations (not expecting an universe as big as NMS). Main story obviously which drives me to play the game in first place and finally romances. I could've picked "Quality: Fleshed out and Solid, does not feel rushed, incomplete, or parsed" instead but since the game's been under development for a long time, I believe BioWare is doing a fine job in crafting ME:A well.

I would like to add another thing. Diversity among new alien species and etc.

If the number of hair threads were any indication, decent enough customization would be great. Armor and casual outfit choices please! Combat and character interaction would also be my preference since the Mass Effect story was simple but still fun. Where it pulled me back repeatedly was the squad, the NPCs and enemies. Their dialogues, reactivity to the choices Shepard made could vary and I wanted to see all the outcomes. Combat really added to the experience for few things made life enjoyable than a well placed sniper's shot.