The starex will be softer, even when unladen.
The everest will be stiffer if you're alone... but it will have a much more comfortable ride when loaded (and as you describe it, mukhang talagang pupunuin nyo talaga yung sasakyan).
I can vouch for the chassis of the ranger/everest. 10 years na yung ranger namin, and so far, the only things we've replaced in the suspension are the pitman/idler arms(once), wheel bearings(twice) and suspension bushings(once) for the front. Ball joints, tie rods, center linker... OEM pa lahat.
and the rear suspension is nigh indestructible (palit kami ng bushings lately, though).
Engine? the WL on our ranger has run 236,000 kilometers... with no overhauls

basta TLC e.
the everest will fit mazda and ford (and ford ranger) parts. Mazford banawe will be your best friend in sourcing parts for the everest. Haven't really have had problems sourcing parts since more than 10 years on the market na yung model
Diesel consumption... the everest is a tad bit on the thirsty side sa city... around 6-8 km/li. Will be better on the highway though.