Start by analyzing your spending patterns. If most of your spending is spread across many categories, a flat-rate card like Citi Double Cash (2% on everything) is simplest. If you spend heavily in specific categories like dining or groceries, look for cards with bonus rates in those areas.
Consider pairing cards for maximum returns — a flat-rate card for general spending plus a category-specific card for your biggest expenses. The Chase trifecta (Freedom Unlimited + Freedom Flex + Sapphire) is a popular strategy.
Don't overlook sign-up bonuses, which can be worth $200-350 in the first year. Also check the intro APR offer if you're planning a large purchase.