There are many factors to consider when buying travel insuance
1) How frequently do you travel?
If you travel more than 4 times per year with each trip lasting more than 7 days, then it may be worthwhile purchasing an annual multi-trip insurance.
2) Are you travelling alone or with someone else?
A family plan covers both the policyholder and his/her family members or travelling companion. It usually result in savings on the premium paid.
3) Do you have any existing medical condition
Check to see if your travel insurance provider covers for medical evacuation or treatment required as a result of pre-existing conditions
4) What activities are you planning to do on your trip?
Read the terms and conditions of the travel insurance provider on what leisure activities are covered. (Eg, Hiking only up to 2000 metres altitude or deep sea fishing is not covered etc.)
If you are planning to drive, you may want to get a policy that provides rental vehicle excess cover.
In summary, go through the travel insurance coverage in details before deciding on which policy to get.