I’ve played the original 4-5 times and the remake 3 times.
The remake has technology on its side, so where the original was trying to be ambitious, the remake fleshed it out much more (zero-g combat, ADS cannon missions, and going back to previous locations).
The original has much better dialogue, and the characters were a lot more believable. The zero g is more primitive but it still works well. The original also made running out of air more of an issue. I never ran out of air in the remake.
Both games are vastly replayable for the same reasons. Upgrading guns, finding artifacts, and trying harder difficulties.
They’re both really good, I can’t say which one I like better.