Depends on you. I was using a smartphone + a feature phone from 2013 to 2017 because I needed to use 2 SIMs & never found a dual SIM smartphone meeting my requirements back then. My current phone is single SIM & I have 2nd SIM on my old smartphone, but not using 2nd SIM because of high cost these days.
Before jio entered, I could easily manage 2 SIMs for under ₹200 pm. Now in their quest to increase ARPU (avg revenue per user), costs have increased. So I just spend ₹200pm on my main SIM. Surely data is more now, but I can't have a SIM for just calling at low cost. All those unlimited SIM validities are gone.