السلام عليكم ورحمة الله وبركاته May Allah elevate you in rank AhsanAllah ilayk. Which knowledge is most beneficial to seek, if the aim is to increase ones emaan-- so which knowledge increases emaan the most? As I'm trying to combat my low emaan with worship and seeking ilm, also any other advice?

Tadabbur of the Quran. Imam Ibn Baz was asked how iman is strengthened and he began with pondering the Quran and being devoted to reciting it, for in it is what tells you of the Hereafter, of Paradise and the Fire, and of the names of Allah and His attributes, and he said whoever ponders the Quran, his iman becomes strong. After that he mentioned the hadith and the character of the Prophet ﷺ and his Companions, then taking account of yourself and remembering death, then the company of the righteous, then attending the gatherings of knowledge. He also said iman increases with obedience and decreases with sins, and that bad company and heedlessness weaken it.