UOB PRVI or CITI PM?

I'd take Citi PM for two reasons: Miles that never expire, and miles that can be earned from the first dollar.

I hate to be awarded nothing because I bought a discount pack of wet tissues at $4.90, then go home and find 100K UNI$ wiped from my account because I forgot to transfer them out to KF (where another 3 year countdown starts).

However, if your expenditure is generally high, the UOB PRVI has its merits, and you'd also be able to accumulate miles faster to burn them, since you have high expenditure. If you don't want to go through the trouble of calculating which card earns more miles based on a sample of your expenditure, I'd rather stick with Citi in this case.

Citi PM is better because it has no expiry date while Privi has an expiry date which forces you to convert to Krisflyer and then you are subjected to a 3 year expiry date from the time you convert to krsiflyer.

This forces you to plan more. However if you are a large spender concentrating mainly on miles, just take UOB Prvi as you will have enough miles in 4 years to redeem business class flights