There was a huge evolution in steel alloy while nothing happenec for titanium, the alloy used for bike frame is the same as 20 years ago.

Titanium is a great material but welding is a major issue: is there is oxygen contamination during the welding, then sooner or later, the frame will break and its impossible to detect this problem when buying a titanium frame.

For me currently, the best material to build bike frame is stainless steel like Reynolds 953 and Columbus XCr that allow to build frames almost as lightweight as titanium but with a better efficiency and no risk of contaminated welding..