If you are lucky go merry type and do not want to take any risk in life than PPF is the best bet for you. However it has its inherent risks in investment and same are as elucidated below:
Returns are extremely low which are eaten by inflation. Thus you may see your money doubling in 8 years but it will be at same level as inflation will eat away all the returns. Have a look at fruits and vegetable prices eight years from now and you will understand what we are talking about related to inflation. What your Rs 100 can buy today may require Rs 200 to buy the same and thus your returns will be nil.
This type of investment is only suitable for a conservative investor who is looking at preserving the capital and may be more suitable for people who are looking at safety first than returns.
However if you are looking to beat inflation than none can beat the intraday trading and you can check out sure tip of the day.