-Keep the inventory system! Loot from Me1 was terrible. I was swimming in credits and omni gel. Cause in reality, YOU HAD NO NEED FOR THEM. You could just find the best weapons or amour in crates.
-Scanning planets was a bit better, but it was still a pain in the ass to scan a GIANT planet which only has a "Moderate" level of resources on it. It was a lot better of a system, but still a bit too tedious.
-Spaceship battles. Like you and two squad mates enter 3 space jet-fighters and battle along side with the Normandy against another enemy ship and space fighters. It would put better use to the upgrades you can buy for the ship. Plus it would open customization of the space jet-fighters.
- I liked how they handled talking to your squadmates in ME1. They had something new to say after every main mission. None of that "We are building a consensus." bullshit. Also it was cool how you could invite your partner to your cabin and have SOME interactions, but you should open up a WHOLE new dialog option with them. Like lovey dovey stuff, or some jokes about the game universe.
Also, NO MORE JACOB TAYLORS. Most boring character ever.