Love titanium, something so cool about it. It’s like steel with no downsides. I’ve got 5 ti bikes and a few ti watches, one of my favorite pieces though is my snow peak double wall titanium mug.
Though it's heavier than an insulated plastic mug, and _way_ more expensive.
Maybe anodized titanium would work better? I don’t know what the chemistry behind the problem is, but even stainless steel kills green tea after a while.