Upgrading old server

Hi All,

We've decided to upgrade our PostgreSQL production servers. First task 
is remove an old v7.14 version. It was supposed to be upgraded to a v8.4 
server. The server was installed, several databases where released here 
but v7.4 was never migrated. The plan is pg_dump this database and psql 
it to existing 8.4 server. After this, we'll pg_upgrade. In order to 
make some tests to be ready for production server I'd like to know what 
would be the best approach: upgrade to v10 or maybe v11? Or start 
upgrading to 9.6 and if everything goes fine migrate to v10/v11?

If is useful: server is CentOS 6.8.

I've installed succesfully a backup of the old v7.14 version in my v8.4 
test server (with some help of psql-admin list), and now that I've 
studied a bit about pg_upgrade-ing I'm going to upgrade installed PG 
version to the one that's the best for this situation.


Thank you all,

Ekaterina