Definitely go titanium... and commercial pure titanium, not aerospace titanium alloy (it's a safety thing - EMS can cut CP titanium bands off your finger with stock equipment, they may have to resort to cutting your finger to remove titanium alloy in a pinch).
As for sites, I know a lot of folks go Etsy or Ebay with this stuff, but the absolute best titanium band maker I've found has been Ed Ferguson at
Cascadia Design Studio. We shopped and looked around online and in stores for months, and we went with Cascadia for numerous reasons including interior shape finish. Great reputation and top notch craftsmanship at a very affordable price from a jeweler who's got a long standing track record, especially by Internet standards.
Go with whomever you feel most comfortable, but at least include them in your search.