Guys here is the scenario

we have 30 different clients.currently running one db and one instance(medium configuration).getting better big configuration.
is it better to create 5 clients per instance.
we have tons of data in each table in the range of 5-10 million rows .I say my database as OLTP tooo...

So wchih one is th ebest option and why do you all think so....
1 DB 1instance for all clients vs 1 DB multiple instance for a group of clients --- Which one you reccomnd