Because this is HLP and therefore I disagree with almost everyone about almost everything, ME1 = best ME. Obviously not as polished as its successors, but it had amazing and unique ideas that were abandoned and retconned to be replaced with bland generic crap. ME3 tried to recover but didn't make it all the way.
ME: Great storyline, quite good characters, awful gameplay (my worst shooting experience in video games I swear)
ME2: mediocre/weak storyline (slowing the macroplot down),brilliant characters (I was so pissed that none of them were our squadmates in 3, except Garrus and Tali), good gameplay.
ME3: average storyline with tons of bad writing as mentioned above, good characters (Citadel DLC brings back ex-squadmates so it's a lot of fun) and the best gameplay and combat system of all trilogy (something the Andromeda bases on, so this aspect of the game shall be taken care of properly).
To my personal taste, I had the best fun with ME2, despite it's lack or macroplot development. Best squadmates with their unique stories. And hey, we are Cerberus, doing the things Cerberus was meant to be doing, not being a damn indoctrinated cannon fodder, because the devs needed some non- Reaper humanoid enemies for the player to shoot at! Such a waste here... I would be so awesome if we had a choice after ME2 to stay on TIM's side (and later help him fight- off the indoctrination or just take him out and take his place) or rejoin the Alliance. Something like in The Witcher 2 where at some point we ha to pick a party we wanted to help.
One more thing I like in Andromeda is that there is 99% certainty we will not see any "Alliance". I don't know why but I was always annoyed when their brass was around, maybe except Hackett and Anderson.