I think the United and Hyatt cards are your best options, but keep in mind that they are all Chase cards. From observation, Chase typically allows approximately one card application per 30 days, but many people have been able to get a second Chase card approved by calling the reconsideration line and explaining why they want the card to a live analyst, and possibly moving credit lines from existing Chase cards.

Factors to consider:

Hyatt's 2 free nights expire in a year, so make sure you will be able to use them during that time period. Check locations you want to go to see if they have a Hyatt. Hyatt does not have a big presence internationally except in a few large cities like Paris.

United miles are often considered the most valuable, see this article. Rumor is that a larger United Chase card offer will be available to the public at the beginning of the year, so you might want to wait a couple months. Someone leaked an upcoming offer in October and Chase retaliated by postponing the offer.

British Airways has severely devalued their miles program and charges large fuel surcharges on its own flights, see here.

I would sign up for the Sapphire card now, and wait a couple months for a better United offer.