I really want a return to the amazing soundtrack direction of Mass Effect 1 rather than what was in ME 2/3. Presidium forever *swoon*
My idea for a Mass Effect game is an entire game set in a massively open world Presidium, where you go on quests and such here, and dungeons are generally some 'trip' off to some planet, a number of preset destinations, but some dungeons exist on the Presidium itself too.
Basically in the game you'd exist as some sort of investigator in the Presidium covering some case, and obviously you'd have to search for clues and be social and use your prowess with language or violence to get past barriers, but eventually the mystery will tie into larger ones involving the ME universe.
I dunno it's much smaller in scale in some ways, but larger in scale in other ways. But I just think the series needs a new direction after it went off the rails in ME3, not necessarily in gameplay but in story focus (although I could use a heavy return to some of the more stat depth of ME1).