Hi John,
Two replies, two preferences - can't get fairer than that! :lol:
MY two-penneth - well MDF's is bloody heavy so better have good anchorage for wall cupboards. MDF's available water resistant I don't know if laminated chipboard is, but either way with full lipping, chipboard' be fine. I'd go with the notion that pullout resistance in chipboard might be a little better than MDF but it all depends on the grade. Cheap grade chipboard a la budget flat packs definitely s**te. "Quality" bought kitchens all seem to be MDF.
But for my money when I do my kitchen eventually, I'm going for carcass framed construction. Appropriate hardwood for visible elements and good quality softwood, spray-finished for the rest. Carcass/frame also has advantage of economical use of material, WW satisfaction, and light weight.
cheers,
Ike