If the pros/cons are apparent, rank those items. An obvious problem (like a big cost difference) may speed up the decision. If there's time, prototype both; e

If the pros/cons are apparent, rank those items. An obvious problem (like a big cost difference) may speed up the decision. If there's time, prototype both; explore any claimed advantages and find some disadvantages. This will make any decision easier to accept. If the two developers are regularly coming up with "equally good" solutions, consider alternating their decision power on projects (e.g. project A, developer 1 gets to decide; project B, developer 2; project C, developer 1 again...).