Star Alliance is made up of several airlines from different countries, there are some similarities in each one of the programs, but there are many different aspects to keep in mind. It is kind of hard to say which program is better, in some ways it is a matter of priorities and knowing what is important for each person. Some programs have as a main advantage something you may not care about, but others may have what you are looking for.
If one does not travel frequently, but still takes a couple of long haul flights a year, a good option may be Asiana or Egyptair. Asiana offers as a plus the fact that miles expire only after ten years. Both airlines offer two years for elite qualification. Another of the good perks of Asiana is that one can enroll family members in the same account.
If status is a priority Aegean Airlines may be the answer since the requirements to get to Silver and Gold status are the lowest among Star Alliance members.
If one travels sometimes in other Middle Eastern carriers such as Emirates it may worth to take a look at Tap Portugal and South African Airways, these two companies offer the possibility of earning and using miles in Emirates. Asiana once again may be a good deal, since they have as partners Qatar and Etihad.
If what matters is recognition as a business traveler Lufthansa, Swiss and Scandinavian are worth it to take a look. These airlines offer great deals and perks to the higher tier members. Their lounges in the airports are amazing and many of their fees are waived when you are elite.
Turkish airlines lies in the middle of everything, their service is excellent, their redemption charts are very good, but what probably makes them stand out is the fact that they are almost always willing to match your Elite Status from other airlines.
Singapore is a great airline, with excellent business and first class cabins that are desirable by many. If one wants to book with them it makes sense to accrue miles in their loyalty program since they make available the best deals for their own members.
If one travels a lot in economy probably what really matters is the ability to redeem miles. United and Avianca are the best for that, they make available not only their own flights in their reservation system but the process to book an award flight with a partner is extremely easy. Another plus is that they do not charge fuel surcharges on their awards or in those with partners. We feel that these two airlines offer probably the best loyalty programs for the normal traveler.
Something good to keep in mind is that one has not to necessarily be member of program of the airline of their own country of residence. Membership to the loyalty programs of the airlines are open to almost anyone. There are some requirements from airlines to get Elite status, for example United enforces the fact that a traveler should fly a certain number of segments to be Silver or Gold.
The best thing is to shop around, the rules of the programs can change fast, it is a good thing to read the fine print for each one of the programs and to choose the one that best fits one’s own needs.