Is it permissible to partner with the Saudi American Bank, which is less expensive and offers better service in stock trading, instead of Al-Rajhi Bank, which suffers from flaws, given that Al-Rajhi is an Islamic bank?

It is not permissible to deal with usurious banks except out of dire necessity. Allah has forbidden usury and has threatened those who consume it with war and painful torment. The Messenger of Allah, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses, and they are all equal. Therefore, a Muslim must avoid usurious banks and seek out permissible alternatives. Furthermore, those in charge of Islamic banks must facilitate transactions and improve services to attract Muslims, for they are guardians at a frontier of Islam, and they must not alienate common Muslims from dealing with them.