Mejo di ko gets yung tanong sa title. Anong magandang sidewinder?
If you mean kung anung pinaka magandang sidewinder missile. The latest most advance model in operation is the AIM-9x (in your picture) however, wether the fa-50 is compatible with such missile is a question. For one, a helmet mounted display and targeting system is required to use the aim-9x to its full potential. I dont think the fa-50 will have one. Better stick to the less capable and less expensive variant nalang.
If you mean what missile can be an alternative to the sidewinder. I believe the Israeli "Phyton" family of missiles is supposed to be compatible with the fa-50.
Other missiles in its class are the European ASRAM and IRIS-T. Again if they are compatible.