Are titanium valves better than pig valves for replacement therapy?

Depends. The decision to use a mechanical or biologic valve depends on many factors, such as age, medical conditions, childbearing expectations and preference. Mechanical valve last longer but require anticoagulation with its associated problems. Biological valves do not cause blood clotting on their surface but do not last as long and in young patients may require another valve replacement over time.
Maybe. Titanium valves will last longer than porcine valves(maybe>10 yrs) but generally require anticoagulation(blood thinners) which imparts a risk for bleeding and at present requires monitoring of blood. In old people, pig may be better choice while in younger people, who don't drink heavily or have risk of falling, titanium may be better because of longer life expectancy.