List where you spend
Go through a few months of statements and note your biggest spending categories. A card's bonus categories only help if they match them.
Read the information box
Check the interest rates and every fee in the information box on the application, not just the annual fee.
Estimate a year of rewards
Multiply your yearly spending in each category by the card's rate, as in FCAC's examples. With no fee, that total is the card's benefit, as long as you pay in full each month.
Check foreign currency and insurance terms
If you spend in other currencies, find the conversion charge. If insurance matters to you, read the card's certificate of insurance before you rely on it.