As others have said, they are very different games. As such, you have to consider a few factors in your purchase:
1. Time of play: O&L is a relatively long game and has a somewhat long setup time. While I haven't played Tzolk'in yet, I would guess you could finish a game in about 1/2 -2/3 the time it would take you for a game of O&L.
2. Mechanics: O&L is very much an engine building sort of game. You create a landscape and everything you do on that landscape interacts with each other. Tzolk'in is much closer to your standard worker placement type of game. You generally focus on a strategy and go with it whereas in O&L you have to consistently build on an idea to be viable (some could argue this, but for the sake of generalization...).
3. Who you are playing with: Both of these games have an acquired taste but I think Tzolk'in has that "oh neat" factor more than Ora & Labora. If you're trying to wrangle new people in to the genre, Tzolk'in is definitely the way to go. Moreover, O&L is kind of a hard sell unless someone is really interested in playing it. That doesn't make it any less of a game by any means, it's just not a game that screams "play me" when you look at the box.
4. The Puerto Rico effect: O&L is definitely a game that you can consistently get better at over time due to knowing exactly what will be happening in future parts of the game. Tzolk'in has a bit more randomness as goals will change on every play. If you're looking for variety, then this is the way to go.
I think if you're really interested in making the Euro jump, both games will be a great choice. As a current owner of O&L and a pre-orderer of Tzolk'in, I am quite certain one will not be replacing the other.
1. Time of play: O&L is a relatively long game and has a somewhat long setup time. While I haven't played Tzolk'in yet, I would guess you could finish a game in about 1/2 -2/3 the time it would take you for a game of O&L.
2. Mechanics: O&L is very much an engine building sort of game. You create a landscape and everything you do on that landscape interacts with each other. Tzolk'in is much closer to your standard worker placement type of game. You generally focus on a strategy and go with it whereas in O&L you have to consistently build on an idea to be viable (some could argue this, but for the sake of generalization...).
3. Who you are playing with: Both of these games have an acquired taste but I think Tzolk'in has that "oh neat" factor more than Ora & Labora. If you're trying to wrangle new people in to the genre, Tzolk'in is definitely the way to go. Moreover, O&L is kind of a hard sell unless someone is really interested in playing it. That doesn't make it any less of a game by any means, it's just not a game that screams "play me" when you look at the box.
4. The Puerto Rico effect: O&L is definitely a game that you can consistently get better at over time due to knowing exactly what will be happening in future parts of the game. Tzolk'in has a bit more randomness as goals will change on every play. If you're looking for variety, then this is the way to go.
I think if you're really interested in making the Euro jump, both games will be a great choice. As a current owner of O&L and a pre-orderer of Tzolk'in, I am quite certain one will not be replacing the other.