My preferred airline is Delta. Having a credit card where I can directly benefit from spending and turn into skymiles is one of my travel hacking strategies.
Especially useful for business travelers, if you love the Marriott brand of hotels, then getting one of the Bonvoy Cards can lend you many benefits. This card is by Chase
It's encouraged that entrepreneurs should separate their business and personal expenses. This is a relatively easy card to obtain and there are benefits that you can accrue just by doing day-to-day business.