Caveat: If you aren’t prepared to pay off credit cards in full every month, DO NOT get cards for the sake of any rewards. The interest rate will negate all reward earnings. You should not compound debt with more debt.
IMO, the best way to really rack up points is to not focus solely on one particular airline but focus on a “bank” of points that can be used for multiple airlines. Chase, Amex, and SPG are probably the three popular and more useful point banks mainly because of their vast number of transfer partners. There are other cards with similar benefits but you’d have to look at each one to see which one(s) are most useful to you.
I will say that the majority of cards to have some overlap. Lounge access, Global Entry reimbursement, and some form of travel credit seem to be typical now of these cards. The important distinctions among the cards is mainly their transfer partners. Although it’s true that through airline alliances, you can pretty much fly any airline you wish, that doesn’t always mean you’ll you get the most bang for your points in terms of redemption rates.
A word of caution to these cards with travel rewards will typically have an annual fee. And the fee isn’t cheap. So you would really have to be able to justify the cost of the card with the number of times you travel a year. I glad pay the $450/year fee for the Chase Reserve because it makes sense for me. I feel like I travel more than enough times per year to more than justify the cost of the fee. However, that doesn’t mean it’s for everyone. I still go through my wallet every year and reevaluate the importance of the cards I have in my wallet. If the time comes where the fee can’t be justified, it’ll be the first to go.
Credit cards are a great way to earn points toward travel and can really go a long way in making aspirational travel affordable or ease the cost when going on a family vacation. But remember to always pay off the cards in full every month. Otherwise any rewards you earn will be wiped away by the interest fees.