[Which is better: taking the concession (rukhsah) or the strict ruling (ʿazīmah)?]

Answer: Each has its merits. Taking the rukhsah is preferred by considerations such as:
1. Allah Most High legislated concessions for His servants—out of ease, relief, and mercy for them.
2. The Prophet (May Allah bless him and his family and grant them peace), on his journeys, would avail himself of concessions, combining between the two prayers—either at the beginning of the earlier time or in the time of the later one.
Source : Min Thimār al-ʿIlm wa al-Ḥikmah vol.1