Ontario skeds have been in a state of flux the last six months with the de-peaking of the SDF sort. More little flights, like PHX-BFI and MCO-MCI that don't touch a major sort. And we've been doing a bunch of turns out of SDF, occasionally two in the same duty period. Anyway, there's something for everybody at ONT, the only question is if your seniority can hold what you want. Generally, if there's a UPS flight to ONT from where you live, you're in great shape. A commute from PNS or SAT will suck regardless of your seniority. And regardless of your airline, too, come to think of it. If you're junior but want Asia flying, your best bet will be the VTO's, which are a box of chocolates. If you're junior but are happy to do airport standby you're in luck. Lastly, in general the skeds have been sliding downhill over the last year. The crews are awesome, hand on the heart, and that can make all the difference. Of 100+ captains, the number I'd prefer to not fly with is one, maybe two.
Looking at the MIA schedules, from the point of view of a commuter, that can be held by the lower half of the MIA list, a dog's breakfast comes to mind. If you live in domicile and are a vampire they're the best you've ever seen.
In any event, if you're asking this question, you're probably going to retire rich, so please keep that in mind. And this is all coming from an above-average whiner.
Best wishes to you, and as always, YMMV.