Answered by Ustadh Tabraze Azam
Question: Am I suppose to choose two surahs to recite before takbir, or can you just recite whichever surah you want after the takbir?
Answer: Wa alaikum assalam wa rahmatullah
I pray that you are well, insha’Allah.
It is disliked (makruh) to fix specific surahs to recite during the obligatory (fard) prayer. For instance, always reciting Surah al-Dahr and Surah al-Sajdah during the Fajr prayer on Fridays as it indicates preferring part of the Qur’an at the exclusion of the rest.
However, this dislikeness is only if:
 You consider them to be necessary or,
 You are the imam and reciting them regularly may lead some people to regard their recitation as being necessary (wajib).
Otherwise, there is no harm in doing so.
[Ibn `Abidin, Radd al-Muhtar]
And Allah alone gives success.
Checked & Approved by Faraz Rabbani