The small % you get on each purchase is crumbs, but the cookie is the big sign up bonus you can get. For the past several years I've been making about $2k/year from that, which is so much more than the % bonus that I don't know why anyone would care about getting 3% back rather than 2%. Like if you are that worried about your money, take the free $2k first.
Do you have a system or tool for finding card offers with signup bonuses? Also (this is possibly common knowledge but) your credit score is negatively impacted not just by % of available credit utilized, but also by average age of credit accounts. If you're going to want a significant loan (eg a mortgage) in the forseeable future, something to keep in mind.
Not endorsing, but these are the ones my "newsletters" email account subscribes to:
* https://yourbestcreditcards.com/ for credit card bonuses
* https://www.frequentflyerbonuses.com/ for hotel, airline and other travel programs