Replicating two PostgreSQL databases without using master db
As far as which server Bucardo should run on, if both of your servers have the same resources, I would just pick one, because in multi-master, with two servers, the bucardo daemon won't have anything to do in a situation where the other server is down anyway. When the other server comes back up, you should just be able to restart the bucardo daemon and have it sync from the server that didn't go down.

https://mail.endcrypt.com/pipermail/bucardo-general/2013-June/001882.html

If you need something with HA, then, I would ask specifically on the bucardo-general mailing list, which is a wealth of knowledge.

You also might find these resources useful for dealing with Bucardo, in addition to the mailing list and the documentation.

Bootstrap Bucardo Multi-Master

Bucardo Multi-Master for PostgreSQL

Conflict Handling with Bucardo