For a pan of the size you desire, I would definitely go for aluminum, perhaps even unlined if all you will do is boil water. I love my mini-Trangia pot, but it is a little smaller than what you want. There are lots of options out there.

Aluminum isn't as tough as titanium. I had an Optimus fail on me last year. It was only thirty-five years old (and my main item for most of those).