I don't care how much better JB's work rules are compared to AS, it is not different enough to offset the pain and expense of a trans-con commute. The LGB base for JB is small, senior and shrinking, the LAX/SNA is base is super junior, and flies both the both the 737 and Bus, making it easy for anyone who wants it to get it.
Upgrade time - it will be awhile for anyone getting hired right now no doubt. Dont even think about upgrade it is such wild speculation tha you should just presume that you will be an FO UFN. If you are happy with the FO pay scale compared to where you are now then you should go to Alaska.
Work rules - at Alaska and JB both need work. no doubt. The problem with work rules is that they will change over your career at any airline and what is a good work rule for one pilot is crap for another. PBS or Hard line bidding; hotels at the airport or downtown; RAP's throughout month or bid for daily; make as much money as you want or upgrade faster with a strict monthly maximum.
I think the choice between JB and AS for you seems obvious. And if you get the chance to go to Delta or AA or United then you absolutely make the jump.
Good luck