Note the Premier bonus is a one time only deal: "Offer may be earned for a maximum of one time and is not combinable with other offers."
For OAK-PHX as a 1K, earnings could be over 7k miles for one flight in the 100% earning fare classes, a little better than you'd earn on a comparably priced UA ticket.
I've flown JSX a number of times and overall prefer the mainline carriers. The biggest consideration for me is it's much less convenient getting in and out of the private terminals.