Question: what is the best rewards credit card to have?
Answer: Top cashback credit cards. Amex Everyday: fee-free + 5% intro rate, up to 1% after. Amex Platinum: 5% intro + up to 1.25% after, £25/yr fee.
Top 'close to cashback' cards. Amex Nectar: £120 to spend at Sainsbury's, Argos etc. ... 
Top supermarket and stores' cards. M&S: £25 bonus vouchers.