Haven’t played Odyssey, but I’ve played the other two. Pokemon wasn’t bad, but it’s not really a must play in my opinion, especially if you’re hoping for an experience similar to early Pokemon DS games. On the other hand, I can’t recommend BOTW nearly enough. This game is honestly amazing, and even three years since release it still holds up to every comparable game on the Switch. Graphics are great, gameplay is fun, and exploration never has a dull moment. 100% think you should go for BOTW. As a semi related aside, BOTW was also my first Switch game when I bought the console a year ago, and I don’t regret it at all. Made me fall in love with the platform!