In my personal opinion, the best order would be the publishing order. It's the order they were written in and for the most part is pretty straight forward. The main stories, in order of publication:

1. Ender's Game
2. Speaker for the Dead
3. Xenocide
4. Children of the Mind
5. Ender's Shadow
6. Shadow of the Hegemon
7. Shadow Puppets
8. Shadow of the Giant

However, ths in-universe order is a bit different:

1. Ender's Shadow
2. Ender's Game
3. Shadow of the Hegemon
4. Shadow Puppets
5. Shadow of the Giant
6. Speaker for the Dead
7. Xenocide
8. Children of the Mind.

In the end, it's up to you. This list also doesn't include the many other books in the same universe, it's just the main ones.

In my personal opinion, the best order would be the publishing order. It's the order they were written in and for the most part is pretty straight forward. The main stories, in order of publication:

1. Ender's Game
2. Speaker for the Dead
3. Xenocide
4. Children of the Mind
5. Ender's Shadow
6. Shadow of the Hegemon
7. Shadow Puppets
8. Shadow of the Giant

However, the in-universe chronological order is a bit different:

1. Ender's Shadow
2. Ender's Game
3. Shadow of the Hegemon
4. Shadow Puppets
5. Shadow of the Giant
6. Speaker for the Dead
7. Xenocide
8. Children of the Mind.

In the end, it's up to you. This list also doesn't include the many other books in the same universe, it's just the main ones.