2 Identical Servers/SQL Servers Processing Transactions w/ Merge Replication Edited entire question for clarity.

Scenario: Have 2 identical SQL Servers on separate servers, processing transactions from different applications simultaneously while being completely synchronized (example mobile apps server 1 and web apps server 2).  

We are going to use Always On to fail over one server to the other for maintenance and vice versa however, when maintenance is complete, both servers will be once again online processing transactions from our various applications and synchronized.  

Trying to solve a request from a client to be online, even during maintenance, with 2 synchronized servers, each processing transactions from different applications.  

What is the best approach to keep them synchronized?  Was leaning towards merge replication.  



Current ver. SQL Server 2012 SP3-CU4

Thanks
Have you considered Peer-to-peer transactional replication?
You can find out more comparison here.


  Peer-to-peer transactional replication:  Use When...
  
  
  Replication is used to improve scalability and availability.
  Minimal latency is required.
  Data is not partitioned among Subscribers.
  Conflicts typically do not occur, but they must be detected if they do. 
  
  
  Merge replication:  Use When...
  
  
  There are a large number of Subscribers. 
  Data is replicated to mobile users.
  Replicated data is frequently updated at the Subscriber.
  Data filtering is needed so that Subscribers receive different    partitions of data.