Where is the best place to park S250k?

There are many areas which you can park your funds.

For Low risk,

Fixed Deposits, Singapore Savings Bonds, Citibank Maxigain Account and other higher interest savings account

For slightly higher risk, money market funds, bond funds, which they have some liquidity.

CPF is a 1 way in, so would advise against (both posters earlier have given their reasons and why).

There are several options to park your cash, amongst which Singapore Savings Bonds (SSB)is one of them. However do note that there is a individual limit of $200K for SSB, and you'll need to open a CDP account first, and then ballot for the SSB tranche. Even so, you might not get the full allocation, so you will likely have to spread it over two or three tranches. Rates vary from month to month, but any early surrender will still result in the interest being paid.

High deposit FDs are another option, but as you have pointed out, the returns are around less than 2% and any early termination results in the accumulated interest forfeited.

Regarding CPF:

Any contributions made to CPF will be spread across the 3 accounts: CPF OA, SA, MA, which earn 2.5%, 4%, 4% interest annually, respectively. Do note that the maximum you can contribute to CPF every year is the annu
al limit which is $37740, and seperately, you may top up CPF SA to the prevailing Full Retirement Sum (will confer tax reliefs for you up to $7000)

CPF monies cannot be withdrawn at will, till at least age 55, but you can use CPF OA money for property. So don't treat CPF as a deposit account.