with sphere 6 essential plus & Vcenter essential licenses.
having 3 Hosts (Esxi) with 3 VMs on each, working as standalone on local storage.
2 hosts are in Main Data Center while 1 is in DR Data Center, both Data Centers have SAN Storage.
How to configure cluster of 3 Hosts with multiple storage?
what kind of replication should be between 2 DCs?
First of all what kind of Storage Array you are using on both sites?
Second, you have to think also what kind of throughput you have between your sites in order to create some "streched cluster" and in case of failure of the DR site to migrate all three VMs from the one site to another and if it is enough the current throughput you have in order to enable the storage replication between your storages.
I would suggest also if you can go at least to Standard license in order not to do this "streched cluster" but to create 1 cluster on the one site and 1 cluster (with only one host on the other) and use the vSphere Replication which is supported on the Standard version (I think will be less expensive than to use your Replication between your storages).
We are using HPE MSA 2040 on both sides, there is no replication between the two storage as it requires license and our management not willing in near future.
enough throughput between sites. and secondly we are not using this for critical systems.
going for Standard will not be an easy job for us need to manage as per current resources.
Starched Cluster will work for us to get replicated VMs b/w two sites? and in case of site failure will be available on other site?
Looks really hard on what you want to do without shared storage or replication between the storage.
I would say that you can do it if you have shared storage that can be accessible from both sites so or using something like VSAN. Otherwise there are not a lot of stuff to do.