One resource that doesn't have affiliate links for credit cards is www.doctorofcredit.com
There are beginners guides on both Doctor of Credit (DoC) and The Points Guy. (Note that the Points Guy makes millions on affiliate links but still contains good info.) DoC also has a spreadsheet that shows most credit cards with their current signing offer and historically signing offer.
I'll reiterate Doctor of Credit as an excellent and unbiased source.
Credit card affiliate fees are easily $50-$100+ so most websites will push the cards with the best affiliate fees. Now if a website gives you a lot of good information that you find valuable, why not click on their affiliate link. It doesn't cost you anything, and they make a few bucks for providing you valuable content.
Most credit card rewards come down to sign-up bonuses ($200 if you spend $3k in the first three months for instance) or ongoing rewards based on your spending (3% on restaurants, 2% on travel, 1% on everything else, etc.). This is complicated by the annual fees some of the cards with better rewards charge.