It’s depends, but follow these ideas
1. The root needs to hold all of the MAC addresses and powerful enough to keep up with the changes
– You don’t want a small switch to be the root.
2. You want the root to be in a central part of the network, to provide the best possible data path.
3. If you built your network well, your client to client traffic should be able to travel to the Root and then to the client on another switch with a delay that is NOT noticeable.