PPF is the safest of the three: a government-guaranteed, tax-free return currently around 7.1%, with a 15-year lock-in. It suits money you genuinely won't need for a long time and want zero market risk on.
ELSS (Equity Linked Savings Scheme) is a mutual fund with the shortest lock-in of any 80C option — just 3 years — and full equity market exposure, so it has historically offered the highest long-term growth potential of the three, along with the most volatility.
NPS sits in between, with market-linked equity and debt exposure similar to ELSS but locked in until retirement, and it comes with an extra ₹50,000 deduction under Section 80CCD(1B), over and above the ₹1.5 lakh 80C limit — effectively a bonus tax break unique to NPS.
A common approach: use ELSS for the growth-oriented portion of your 80C since the lock-in is short and manageable, keep some PPF for a guaranteed floor, and add NPS specifically to capture that extra ₹50,000 deduction rather than as your primary retirement vehicle, since its mandatory annuitisation at retirement reduces flexibility later. The PPF and NPS calculators on this site can help you compare actual projected corpus values side by side.