Yeah, in the realm of rewards cards in the US there are cash-back cards, miles cards, and points cards. Cash-back cards just give you a redemption on whatever you owe them for the next statement (you effectively pay $98 or $99 when you spend $100). Miles cards give you per-dollar-spent frequent flyer miles for a specific airline or group of airlines usually plus a sign-up bonus like mentioned here. Points cards are like miles cards, except the points are more flexible and can be converted either to airline miles or to gift cards or to statement credits.
As for the time spent researching. These days it basically non-existent. If you google "best rewards credit card 2019" you'll find half a dozen sites all with similar recommendations all telling you basically "Get this one, then in a few months get this one, then get this one, then close them and start over in a year. Don't do anything fancy, just spend enough to cash in the sign-up bonus and then switch to the next."
As for the time spent researching. These days it basically non-existent. If you google "best rewards credit card 2019" you'll find half a dozen sites all with similar recommendations all telling you basically "Get this one, then in a few months get this one, then get this one, then close them and start over in a year. Don't do anything fancy, just spend enough to cash in the sign-up bonus and then switch to the next."