Both cards earn 1.4 miles / S$ locally, or 2.4 miles / S$ overseas, and include travel insurance (check T&C). A newly added feature is 3 miles / S$ on Singapore Airlines, SilkAir, and KrisShop purchases.

The AMEX version gets you a bonus 20,000 miles if you spend $50,000 SGD that year as well as a $45 one-way Changi Airport limo service rebate after spending $1k SGD overseas that quarter, but that may be offset by AMEX not being accepted everywhere.

This is a decent 'general use' card (especially overseas) if you just want one card to use and/or have exhausted 4 mile / S$ options, but locally you can get a lot more miles by thinking and planning a bit.

Earn Rate: 1.4 miles / S$ locally, 2.4 miles / S$ overseas
Minimum Income: $80,000 / year
Annual Fees: $406.60 (MC) / $256.80 (AMEX)
Website: http://www.uob.com.sg/personal/cards/credit/uob_prvi_miles_mastercard.html