Martin Lewis has an interesting article on credit card reward schemes at
http://www.moneysavingexpert.com/car...t-card-rewards
Note that when he refers to AmEx Platinum, it's the credit card he means, not the charge card.
The calculator at
http://www.moneysavingexpert.com/rewardsChecker compares different schemes, including BA AmEx, Miles-and-less AmEx and Visa, Lloyds TSB AmEx and Mastercard etc etc. The calculation for the Virgin AmEx white card is wrong, showing GBP 0 value for GBP10,000 spend (unless it's been corrected, I've e-mailed ML).
I'm already rationalising some of my cards. I used my previously good Thomas Cook Visa card for the last time yesterday, spending my GBP120 in TC Pounds to buy some SA Rand. Next to go will be the LloydsTSB AmEx if ML's comparison is fair.