I would love to design my own, and get it made.
The spec:
Made to formula 1 standards using carbon fibre and titanium, therefore very light but extremely strong.
Would have 4 wheels, but 2 would be lockable so the case didn't run away on a slope.
Obviously it would have a folding handle for wheeling, and would have the choice of 4 wheel or 2 wheel drive (using the wheel locks).
The wheels would be larger than usual suitcase wheels, for rough terrain. They would have easily replaceable solid rubber tyres so they would never wear out. Naturally they would have high quality, fully sealed, ball bearings.
I estimate it would cost about £1000, probably made by McClaren F1 racing, so I am waiting to win the lottery.