Of all the games in the serie, the 1st is the one I replayed the most. Still today I got chills during the first encounter with Sovereign and all the realization that came with it. Saren is still one of the most interesting antagonist we have in the series and the lore building is top notch.

Mass Effect 2 managed to improve on many aspects and even if it made the universe larger, it felt small in scope since its more related to the crew of the Normandy. Not many game had me feared for the safety of the characters like this game have. The ending is probably one of the best moment I’ve played in a game.

Mass Effect 3 was definitely different in term of  scope. I know a lot of gamers are bitching about the ending, but every main events in the game serves as a conclusion to the stories that we’re introduced since the first game. From the beginning, it felt like a conclusion and straight from the bat, they showed you that it would not be a pretty and happy story. And that’s the redeeming qualities of the 3rd entry and conclusion.

Loved all 3 of them and I hope the next entry will develop on the consequences of the Reaper invasion and the difficulties ahead in rebuilding the galaxy.

Bonus: I played John, the female option was introduced like an available option only and it showed in its design and animation. It felt like the character was out of place in some cinematics. They improved with the 2nd and 3rd.

But I started the journey with John, ended it with him.

You're making this a little to easy Rol.
2 is the only one where story and gameplay are both tip-top as far as I'm concerned.

ME1 had wonky combat and meh-ish graphics but everything else was great
ME2 still looks decent and plays better. Also added great characters.
ME3 improved gameplay even more but new characters were boring. Only ever played the Extended Cut so I didn't have a problem with the ending.
ME Andromeda has the best gameplay but characters are mostly just copies from previous ME games with a different name and the story doesn't feel as epic.

That's why I'm choosing ME2.

Fav: Mass Effect 2. Played as both.

ME3 forcing MP into the SP was a major fuck me in the ass,
ME2 was fucking up majorly with gunclips, this was just plain stupid in a SF game
ME1 was by far the best outside a slow UI

EDIT: MEA crashed on me twice in the first half hour never picked it up again

1: Great storyline, and some of the more interesting and open-ended missions in the series (Noveria might well be my favorite mission in the entire franchise), let down by clunky controls, a godawful inventory management system, and very repetitive side-missions.
2: A very well-rounded experience, striking a good balance between the combat and other types of mission, good storyline content, an overall more developed world than the first game, and plenty of freedom when it comes to how you go about the storyline. A few aspects of the game are over-simplified, but it's a pretty small complaint.
3: Core gameplay's probably the best in the series, but it feels much more linear than the previous two games, the missions lack variety, and then there's THAT ending.
Andromeda: Quite possibly the worst AAA game of the last console generation, once you leave out the "Games as a Service" titles.

Haven't played either of the mobile games.

So yeah, has to be 2 - though I have a feeling that the Legendary Edition of 1 might close the gap.

Mass Effect 2 is the best. It is lacking in certain RPG elements, but everything else about the game is fantastic.

1, 2 began to be a generic 3rd person shooter, 3 completed that transition.

ME2 - Engaging story, good pacing and memorable cast. Also much improved gameplay and some really fun DLC. One of my favourite games of all time.

Bonus: Male Shep is the only Shep.

Mass Effect 2 is unquestionably the best entry, but the first game is still my favorite. It's got a stronger core narrative, more RPG mechanics, and just does such a fantastic job establishing the whole ME universe. You get introduced to all these different things without it ever feeling overwhelming or like it's just a nonstop exposition dump. The fact that they managed to so seamlessly establish that many different compelling species, social and political dynamics between them, technology, etc...it's just fantastic. I'll never forget what it was like playing that game for the first time.

I prefer playing as FemShep. They're both great, but Jennifer Hale really kills it with the delivery to the point of perfection.