It really depends on your age. At 60 it’s possible the annuity might have to pay out for 30 years, so it wouldn’t pay much per month, while not buying until your mid 70’s would produce a better figure. My FA told me the optimum time to purchase an annuity was between 72-74. I decided against it, stuck to a draw down pension and the DDs can inherit what’s left, less taxes.
Buying an annuity is similar to buying shares - it is what it is on the day. A few days before might have been a poorer purchase, a few days after, better, or vice versa. Worth remembering it’ll die with you and the monthly income added to your DWP will incur income tax.
I’d always take the 25% cash free option first.