oooh, now that's a tough one.
Partly because it could be affected by the customer service in the back end. You can have a great product, and if the support/aftercare is poor then it's not so great.
I guess key considerations here are:
> How has the product weathered the sands of time / coped with technological change?
> How strong is the brand, its ethos and its customer service ethic?
> Does it demonstrate value for money at some level, and give a length of service with trouble free ownership?
After much head searching I'm going to go for the Nikon D3X digital SLR.
It captures your happiest moments in 20 odd megapixel glory. Based fundamentally on the concept of the old 35mm film based Nikon F5 this is a product that can cope in the harshest sandstorm, take photos in the most severe of conditions, has integrated massive technological change into it's fairly diminutive shell, and still manages to capture history as it happens (whether it be world history or just your own). It's a beautiful piece of engineering, well made, dependable, fast, wireless & GPS enabled and well supported. It's a product that has evolved beautifully over 4 or so decades.
A touch pricey, but it still holds dear to the principles Nikon instilled 40 years ago about the ethos of putting the users needs first to enable them to capture the critical image. I don't own one (yet), but one day I would love to.