4D55 Performance
Explorer
Well, I don't think you would find too many parts more ubiquitous than for an Explorer...
From your post it sounds like you've become dead-set on something with airbags, so that would certainly eliminate this gen Ex.
I don't know much about the Monteros, however I can tell you they are not popular at all in my area. I would have the same concerns about walking into Autozone/Napa/O'Reilly's/etc. and everything being a special-order-only item you'd have to wait for.
I'd probably lean toward the Jeep XJ in this case simply because it doesn't have the A-arm IFS that is unlikely to satisfy the 1st & 8th requirements spelled out in your 1st post, however IMO it's a pretty crude vehicle compared to most of the others being mentioned here (and is instead unlikely to meet your req. #3, and some possibility of #5 too).
Good luck.
You need to pay more attention, everything is plentiful in SoCal. First, nothing ever rusts, second the population make everything plentiful. I have purchased several Mitsubishi's out of SoCal over the years. They have all had a few issues so , have to go pickup parts from the parts store, junk yard or dealer. I wished I lived in SoCal because everything is so easy to find and there are some great pick 'n' pulls. My favorite is the one in Long Beach, but there is also a really good one in Sun Valley as well.