Which is the most long lived species?

Thanks! I don't recall who Nakmor Drack is. When I do the Citadel dlc I will pay close attention to Wrex.

Nope haven't played Andromeda, but will after my second playthrough of the Trilogy.

As mentioned, it is proven krogan live longer. Patriarch is among the oldest like Drack since he was around before the Krogan Rebellions.

Wrex was alive during the end of the Rebellions, but younger than Drack, Okeer, and Patriarch. Wreav is another example of one who was alive during those times.

Asari can live over 1000 years but, like everyone, it can probably vary. Probably a few hundreds years plus or minus 1000. Aethyta's parents both fought in the Korgan Rebellions. We don't know when she was born or when her parents died. I got the feeling she was pretty young when they killed each other so she might be in excess of 1000 years. Samara was close to 1000 and she was one of the more powerful asari we encounter. She didn't look like she was dying anytime soon, but we also don't know how aging works from outward physical appearance. Benezia might have been about the same age as Samara though we have no proof. Either way, she looked, IMO, younger than Samara.

Drack is a 1400 years but I don't think Wrex is that old. Okeer is also supposedly around 1400 years old. Don't know the source regarding him.

On the whole, I'd say krogan live longer but probably not by much.

I want to say keepers but they might just recycle themselves and be recreated on a periodic basis.

As for someone else on the Reapers, it's hard to say. Harbinger is the oldest Reaper. It's created from the Leviathans. Whatever the next Reaper it was created from another race it harvested. It had a similar shell but it was the goo of something else inside. The potential human Reaper was being made out of humans. They may not be a singular species at all but a bunch of individuals wearing similar shells.

Edit/Add like 1 minute later: Sovereign says they're something like unique entities so that might be true.

The Leviathans I guess, since we don't know how long they live for.

And... the Rachni... we know nothing about how long they live.