I wanna make a thread on it one day but I genuinely believe as far as combat mechanics go Mass Effect 3 is one of the best third person shooters to exist. People argue that it's Vanquish or Uncharted or Whatever but it's mostly the movement with them that's so good. The actual fighting shooting of enemies is stellar in ME3.
There's so much customisation and combinations as well you can do. The physics engine was a lot more dynamic so you could do crazy stuff like map Liaras biotics to the left D-pad button and Garruses concussive shot to the right. Then tap left and tap right so she raises an enemy into the air and (if you aim slightly to the side) his shot curves and sends them flying off the map. That's how I cheesed my way through most of Insanity.
The customization was great. Granted, I haven't played ME2 for years now, but from what I remember the best squad mates were the ones with assault rifles. Everyone else, regardless of their powers, was just not that great. ME3 really turned that around by making powers much more important and I think every party member had at least one power that could combo. This actually made characters like Kaidan incredibly good because he had two powers that combo'd with both "schools" (tech and biotic)... and to top it off, access to assault rifles.
I was recently thinking about the weapon system for Shepard themselves and how well it's done compared to similar modern RPGs that try to let the player do everything. In a game like Skyrim I feel the removal of classes makes the leveling system and character building feel shallower compared to earlier installments. It's too easy to be anything and there aren't many meaninful choices to be made. BioWare did it right by letting you use (almost) every weapon you wanted to use, but with drawbacks depending on your class and skillset. These drawbacks were impactful, but never to the point of crippling you. A power based class like the Adept could still use heavier weapons like assault rifles, sniper rifles and shotguns, but the heavier the weapon(s), the longer their cooldowns would be. Yet not every assault rifle has the same weight, nor the same handling. And that's not even touching on the mods that influence weight, recoil, etc. All this really forced the player to seriously consider their strategy. For example:
"I'm a Vanguard, so I'm all about charging in and blasting enemies with my shotgun. This does leave me at a disadvantage at ranges my Charge can't reach, which was something of an issue in previous levels. I could equip a sniper rifle, but this extends the cooldown on Charge by a few seconds. I need to use Charge as often as possible because it recharges my barriers and I won't survive long without them in close combat. Can I compensate by being smarter about where and when I Charge? Or should I give up on the sniper rifle entirely and settle for a scoped handgun?"
Et cetera, et cetera.
The funny thing is that the Mass Effect series is famous for its meaninful choices and resulting replayability. But I played through ME3 a dozen times making mostly the same choices every time—it was the combat that made me play the game over and over.