I played all of the aforementioned games and all of them are great, some in their own way (like AC) and some, just because of 'teh awesumness'; RDR was what an open-world Western themed game should be. Its predecessor, Red Dead Revolver opened that door; the less-acclaimed GUN was also pretty ok, if only because the Punisher was the lead vocal (Tom Jane). But Redemption was everything I ever wanted in a Western-themed game...it had it all. I even liked the fact that you only had one experience with a car- and it was like a half mile journey at best. It was really well written, well acted and well developed. Loved it. The best AC game, beyond the first (which, being during the Crusades means its automatically my favorite) is Black Flag. Oh, the epic story arc of Ezio was awe inspiring, but the most fun I've ever had in an AC game was in Black Flag. You play as a sailor turned rogue and its a pretty good story but the best part of that game was the open world- and the best way to traverse said open world was by boat. The sailing aspect was so much fun I logged more hours just sailing (and yes, attacking other ships, and strongholds and towns and islands- you get the drift, so to speak); upgrading your ship with newer, better and more- armaments, shielding, etc etc. I remember when I first crossed shipping lanes with a Legendary battleship- purely by accident and I barely scraped by the lives of myself and my crewmen! And they sang sea shanties- that you had to find first on land. The story became second string once I got on that boat. Oh man, it was pure awesome.
So the latest, Unity- it was good, nice story, great visuals in revolutionary era France- but it was all ON FOOT. No horseback sequences, no carriages, no boats- just the huge island of France and everywhere you went was by foot. Or the teleport cages, but those don't make traveling fun, only expedient.
As for pure epic-ness, Mass Effect hit me like when I first read the Hobbit, or saw Star Wars- took me a while to get my head around it. There have been few games that caused me to take a step back and attempt to see the larger picture- Grand Theft Auto 3, Elder Scrolls: Oblivion, Assassins Creed I, just a few that come to mind. Games that made me think, not just on what was going on at the time, but what was to come, and how to effect it in such a way as to be what I wanted it to be. A lot of games make that promise, but a lot also do not deliver in that regard.
The question is- how much further can they go in games before it gets old hat? There's only so many flavors of fetch-it quests you can go on before they start to mash together; multi-step fetches get old after a while, too. I've seen serious themes explored in games (The Walking Dead series of games, The Last of Us, Heavy Rain, etc), in some instances that made me cringe. As I go on, I find myself wanting that visceral experience over style or popped out graphics, you know? Ten years ago I would've been salivating at the idea of a new Street Fighter or Mortal Kombat (or Killer Instinct, used to love that one) but now I've no desire to play any of those. They look great, but my twitch skills have been slowly perishing and tbh, I need more substance than simple fighters will give me. Guess I'm getting old after all. lol