I almost always travel United now, because of using Newark as my departure hub. I don't think any of the airline cards are worth it - the miles are "worthless" and the annual fee would pay for checking a bag too, so unless you're booking direct and a bunch of flights, it won't really be worth it IMO.
IDK the rest of what you're doing, but for now the Amex Aspire Hilton card gives the $50 credit quarterly on the United Travel Bank, so you could just use one of those credits for checking a bag usually. If you keep topping off the travel bank you could have $200 a year for checked bag fees, and get all the other Hilton benefits without another card or annual fee.
In fact just for checked bag fees, I'd look at any cards travel bennies to see if they'd cover the checked bags dollar cost. I think the Chase Sapphire Reserve would also provide something like $300 a year in travel credit which again would cover multiple checked bags easily.