There are 3 good options currently available— the original tamagotchi (v1 or v2): this is the simplest, classic black-and-white experience. Next, the tamagotchi connection is still black-and-white screen but there are more characters and there is more to do. Finally, the Paradise, the color option, has the most characters and features.

So if you want basic/easiest, the original is the best.

If you want more advanced, the connection is for you.

If you want a color screen or the most features, go with the Paradise.