ME3 had awesome things, I mean, the entire series. Each and EVERY game had amazing things. So, so much. But here are just a few from ME3-
Black Widow sniper rifle..... GREATEST sniper rifle ever, in ANY game I've ever played. Awesome
The MP suite. I gotta admit, I was skeptical at first about the MP suite in ME3. But I loved it
All of Citadel DLC- it is a masterpiece and easily the best content of ME3
Javik. Nuff said. Dude is a great troll and awesome.
Garrus. Just everything Garrus. Classic
James- yep, I said it. James grew on me, Garrus and James were my MADBRO YOLO swag team of BAMFs. James was a true bro.
Leviathan DLC. Awesome, the investigation, the discovery and that ship and the combat on the ship. Awesome. Also..... dat harbinger **cough cough** I mean "Leviathan".
There's a lot more, but that's the standouts for me.