Your have several options to express the comparative and superlative in Egyptian Arabic. An overview.
Does Allahu Akbar mean "God is great" or "God is greater" or "God is the Greatest"? There is no clear answer. There even might be an underlying ellipsis.
The Islamic call to prayer is a tricky construction. In Sunni Islam, the muezzin uses khayr (خير) which strangely denotes a comparative (better). Why?