Hi, makes more sense to buy one that gives you monthly payout to 80/90 or for life?
Life, almost always.(*)
It's easy in Singapore for you, as an individual, to construct your own annuity that pays out for a fixed term. That's called saving and prudent, age and risk appropriate investing, with prudent drawdown. An insurance company "middleman" can really only add cost to this particular endeavor, and you certainly don't need that. Please note that I'm assuming responsible financial behaviors, that you actually do save, invest, and draw down prudently, using quality and low cost investments. If you're incapable of such responsible behaviors, then maybe the power of a premium bill (and an insurance company adding its costs) is the best you can do.
Longevity insurance is different. Most people cannot predict with any sort of precision their lifespans, and so pooling that longevity risk is where the government (CPF LIFE) and insurance companies (life annuities) can offer genuine value for your premium dollar, in that order. CPF LIFE clearly offers the best longevity insurance value per premium dollar.
I would also point out that only a genuine life annuity qualifies as a fully SRS compatible annuity, which effectively stretches the tax advantaged withdrawal period beyond 10 years. That's what the tax rules require: life means life, however long it lasts. Manulife sells fully SRS qualified life annuities.
(*) One possible exception is if there's a reliable and significant bequest in your pipeline, with high confidence. Then a fixed payout term annuity might make a little more sense as a "bridge" to the bequest. But I really struggle to make even that possible exception work well in financial terms.
