I've been thinking about what the main issues of Mass Effect 3 are. Not just the ending, bu the greater mechanical and structural issues which keep ME3 from being anywhere as great as ME2. Besides nit picks about the roll mechanic, the lack of hubs other than the citadel and the pointlessly dull side quests I realized that a major issue with ME3 is that the Companions have no place in the story. Let me go back to ME2 to illustrate what I mean, ME2 is about Squad Members. Through the game you meet them, get to know them, fight with them, and eventually gain their loyalty in a mission where you see their inner demons and get to help them resolve their issues. ME3 lacks that entirely. Instead of loyalty missions and big personal issues which could jeopardize the mission you have petty interactions with each of your squad members that have no bearing on the end of the game. What's that EDI? You want to fuck Joker? Alright than. If you ask me the issue is that whether companions are loyal or not has nothing to do with the resolution of the story. They're not important. How would I address that you ask? I'd suggest forgoing the route of taking ME1's cast minus Wrex and instead make one rule: Everyone on your squad's loyalty effects the end game by way of them being Thought Leaders.

What would the squad look like with that rule? Let me tell you. A note, I'm going to refrain from inventing characters here and will use existing characters from the game who could've easily become squad members. Ready? Here goes.

• Anderson. I know he wanted to be on Earth, but I don't care. Dude is the most sensible human squad mate. He was once on track to become a Spectre, he's a leader of his people, and he's not some random soldier that becomes a squad mate because of coincidences. Only issues would be why he'd take a secondary role aboard the Normandy and what possible loyalty mission could encourage more humans to fight the Reapers.
• Primarch Victus. He's a capable and clever soldier with new ideas in a role he never imaged he would have to fill. Simple story, would be a good set up for a squad mate. Loyalty mission would be the one where you go down and find his son, would be more personal than existing mission. More about him than the son, and him dealing with accusations that he's no good for commanding roles, which he takes hard considering he's in a role he doesn't think he's suitable for.
• Wrex. Simple, obvious, Wrex is the leader of the Krogans. He's a natural fit for a companion since he was already one.
• Legion. Again, obvious.
• Zaal'Koris vas Quib Quib. This one is a bit of a stretch, Tali might be equally suitable for the role of Quarian Admiral Companion (since she's now a companion) but she appears to hold no sway so I'd say Koris would be a better choice as the most credible dissenter to the war. What of Tali then? I'd say let her get injured in the war for the homeworld, have her dying of illness. We haven't seen any Quarians die of illness and Tali is the one we care most about!
• Ka'hairal Balak the Batarian Terrorist from that Citadel Side Mission. The end of that mission was really neat and I feel it would've been really neat if he had been an optional Squad Mate similar to Legion or Grunt. It could give you options to "Turn him into the Citadel", "Just kill him" or "Convince him to serve on the Normandy." I think that his perspective and what he'd have to say about terrorism, the hegemony, and whatever else would be really interesting. Plus you could have a loyalty mission where someone he was once close to defects since he's cooperating with Shepard and you'd have to go sort it out.

That's not the longest list admittedly, and there are some large oversights. There's no one representing Salarian interests, there's no one representing Asari interests and only one human (I'd suggest inventing a Human who represents the colonies who trust Cerebus after ME2 or, alternatively, just have Ex Cerebus guys straight up). Additionally, depending on what choices you make you could lose squad members left and right. If you choose to side with the Dalatrass in curing the genophage you'd lose Wrex. If the Quarians or the Geth die Legion or Quib Quib would be right out. Victus would be pretty dependable but that's about it. However, I'd argue that could be a good thing. It'd mean that it'd be literally impossible to make everyone happy, and make the major choices of the game about the companions as well as their races. If you side with the Krogans you in effect choose Wrex over whatever Salarian option exists. If you turn Balak in maybe Samara (or some other Asari law enforcement officer) joins you since you're serious about upholding galactic law.

I'm not entirely sure if people would like it if it was like this, maybe they prefer the nostalgia of hanging out with familiar faces to having to meet, get to know, and do loyalty missions of new ones, but I think it'd be a step in the right direction.