Hi lostscout,
Here is the story of a man who went trekking in Nepal. In his packing list, he notes that his "electronic" (piezoelectric) lighter stopped working at higher altitudes, while a lighter with "traditional flint" worked normally. I'd suggest a Bic or Cricket disposable. I've read negative things about Scripto, but cannot vouch for that myself. For redundancy, you could even carry a "mini" version of both the traditional flint and the piezoelectric styles. That way, you've got both the somewhat more waterproof one and the somewhat better at altitude one.
Stay safe,
J.T.