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Browse credit cards from a variety of issuers to see if there's a better card for you.
Other than the debate over the value of their Vantage 3.0 scores and their approval odds (often abysmally inaccurate), CK is fine for general comparison although it may not always be up-to-date. Generally, I'll compare the application pages themselves (which list benefits and terms of each card) in separate tabs. And often just using Google can bring up a number of good comparisons by typing in something like Freedom Unlimited vs Quicksilver. Of course, if you have any specific questions about cards or what best fits your particular spending habits, please feel free to ask here!
Nerdwallet is another site that is ok
What exactly do you want to compare about them? If you're looking at basic cash back rates, a website's calculator can be helpful.
If you're interested in using benefits or airline miles, it's best to ask existing customers or read the fine print.
Doctor of Credit usually has really good information. If you want to learn about advanced techniques then Million Mile Secrets is really good, along with DoC.