I was looking into this GWT vs GWT 2e vs Argentina thing a few weeks back. Those who have played it to death had a clear consensus: GWT 2e WITH Rails to the North = GWT Argentina. You really only need one, and you’ll probably stick with whatever you play first. They have some different twists but neither is better, has more longevity, etc.
They said GWT without Rails had a smaller decision space and you’d need to grow into the expansion.
So, as a first buy, the vote was Argentina as you get all the game you need in one box.
I’m also waiting for NZ, though, as it has sheep.
Edit: I guess the unstated implication would be, if you want something a little simpler or cleaner, or want to switch between levels of “how much is going on,” get GWT OG so you can play the base set.
Edit 2: The 1e vs 2e debate remains unsettled. This was the best breakdown I could find. About half of the changes are immaterial unless you’re doing tournament level play. Some are easy to implement at home (larger starting hands for people later in turn order, moving one starting building, larger cattle market). Several, though, seemed really key for enabling more strategies ($1 income when trashing a card, allowing lower value deilveries) or forcing the game to be played the way it was meant to be played (dollar values for Kansas City and Teepee/Bandit spaces).
One of my greatest weaknesses is balance changes, so I shelled out to upgrade.
Edit 3: possibly the hardest part about upgrading was the loss of the Indians / Native Americans. I know it’s a sensitive subject and no handling is perfect, especially in a game setting. But this alternative, erasure, perpetuates the unconscious but comfortable belief that the lands were empty, which we passively fall back on when rationalizing our national identity. That’s worse. I think 1e did a “sufficient” and therefore better job.