Get miles on credit cards

I know this topic has been done to death but I feel the urgent need to share some hidden truths people may not know about. I own the following cards and these are the privileges on each:

1. UOB PRVI Miles Platinum American Express^® Card
Earn 2.5 miles for every S$1 spent overseas
Earn 1.6 miles for every S$1 spent locally
Bonus 20,000 miles every year if you spend more than S$50,000 per annum
Complimentary one-way limousine transfer to the airport

BUT the fine print:
You accumulate UNI$ first at the rate of UNI$4 for S$5 spending. Then you will need to convert your UNI$ into miles. That requires you to fill up some form to link your UNI$ account to your KrisFlyer account, and a $20 fee. Conversion is in blocks of 10,000 for UNI$5000.
To get the limousine transfer, you need to charge travel-related expenses (limited to air ticket bookings, hotel bookings or any travel package from a travel or tour agency) of at least $500 to your card. I haven't used this privilege yet, which brings me to the most problematic part:

This is a AMEX card and is not widely accepted. You may find problems finding merchants that actually do accept an AMEX card. 

Final rate: S$1 = 1.6 miles

2. Citbank Premier Miles Card
Earn 2 Citi Miles with every S$1 overseas spend.
Earn 1.2 Citi Miles with every S$1 local spend (No minimum spend required, No rebate cap)
Complimentary Priority Pass membership (2 complimentary visits per year)
Conversion is available to several types of frequent flyer membership. For KrisFlyer, 1 Citi Mile equals to 1 KrisFlyer mile. There is a $25 fee and this takes 5 working days. Min 500 for each transaction.

Final rate: S$1 = 1.2 miles

3. Amex Singapore Airlines KrisFlyer Gold Card
Bonus 5,000 miles upon sign up
Earn 1 KrisFlyer mile with every S$1.60 charged to your Card.

Earn 50% more miles when you spend S$5,000

Receive an additional 50% more miles when you spend S$12,000

Double KrisFlyer miles for bookings on singaporeair.com

Miles credited directly to your KrisFlyer account

This is a AMEX card and is not widely accepted. You may find problems finding merchants that actually do accept an AMEX card. 

 

Final rate: S$1 = 0.625 miles

Conclusion: I have been accumulating spending on my Citibank Premier Miles card since forever. The rate is reasonable and I don't have to worry about miles expiring.

However, I would start carrying around my UOB Prvi card more often and take the opportunity to charge it if the merchant accepts AMEX card. Then again, going by the need to convert in blocks of UNI$5000 would require S$6250 spending. At the end of the day, I still think the Citibank Premier Miles card makes the most sense.