If repplaying the original trilogy, what will you miss from ME:A?

The combat is gonna miss me, the verticality and mobility of the jet pack is something I absolutely love in MEA,

there is also the facts that there is no class restriction in MEA, something I wanted to have since the first mass effect, making any combination I want with any kind of abilities whatever their branch.

Planet exploration is also way better than it was in the first mass effect where there was repetitive envinronments, here each planets feels different and they are not the corridor exploration of the second mass effect that I absolutely hated.

There is also the crafting system that gives more importance to any kind of matters or minerals I find on any planets.

There is also the viability system, that gives more reward for each quest rather than just credits. Money, just like in any rpg, at the beginning you have not much of it but by the end, you have so much you don't know what to do with it. Here I get Viability point, that gives me permanent bonus for my playthrought that are much more useful than just credits.
Ill also miss the angara, Absolutely love this alien race, especially Avela Kjar : 




For now those are the elements ill miss from mass effect andromeda, there is probably others that are going to come to my mind but at 3 in the morning, those are the only one.

Everything you said, but I can listen to Garrus, Liara, Wrex, Tali, Miranda, Ashley, Mordin, Miranda, the Illusive Man, etc. all damn day. 

Combat. I fired up ME3 recently, and it's so weird in how stifling it feels now. Melee ground pounding, hover-charging, blinking through cover to stab enemies in the face and being able to zip around the map like gorram monkey with a jetpack spoiled me rotten. MEA has broken my attachment to ME3's combat.

The ship. I actually like the Tempest a lot. I love its layout and its more intimate design, and I especially love the bridge.

Kallo. Better than Joker, I say.

Drack. Wrex is great and Grunt is Shepard's quasi-adopted krobaby, but Nakmor Grandpa holds a special place in my heart now.

Ryder. I like Shepard. Shit I'd say I even kinda love Shepard, but I've burned out on that character so the former is a shiny new action figure that I greatly enjoy.

Lack of tech madness. It's nice to not have ancient stuff lying around that doesn't make people go batshit standing around it for too long.

Banter.

Melee.

Crafting.

Combat.

Drack.

Biotic Jump / Jetpack

Melee

The loot system. Not having to scan every corner of a room for an upgrade or item you'll otherwise miss.

Combat.

As of now? I would not miss much, though, there are some good concepts and ideas, alas, they are not done finished/made right (if we would split a feature into few stages like: first idea, initial implementation, halfway through, finished, polished... I would say, nothing is finished. If they manage it to patch things up and finish all the gameplay featues they actualy implemented in the first play, there is just one thing that I would not miss: the lack of squad involvment in the story. Everything else would be just better then original trilogy.)

I'd miss jetpack mobility for sure. I'd also miss the open environments of ME:A. The trilogy was much more of a corridor shooter.

The lighter tone of ME:A has grown on me too. It took some getting used to initially, but the humor is actually refreshing for a genre/series that usually stars stoic military types.

Nothing. Literally. Even combat verticality, as nice as it is in MEA, is something I can totally live without.
Actually that is probably the best summary of how poorly Andromeda turned out - shell of a Mass Effect game...