Egypt's climate is dry, hot, and dominated by desert. It has a mild winter season with rain falling along coastal areas, and a hot and dry summer season (May to September). Daytime temperatures vary by season and change with the prevailing winds.
As a result, you will face minor scams in both countries – but if you are vigilant, it's nothing you need to worry about. Based on the statistics, Morocco is a bit safer than Egypt, though there is an ongoing conflict with Western Sahara.
Both countries are fantastic and I'm sure you'll have a great time either way... I find Morocco a bit more manageable to do on your own, Marrakech is not as big and intimidating as Cairo, but on the other hand Cairo does have a special energy and personality as well. It's not an easy choice!
Casablanca is a more modern, business-oriented location. It still holds an enormous amount of history and interest, but combines that with bustling streets and a title of Morocco's business capital. Marrakech is a more popular tourist spot, combining phenomenal scenery and architecture with a remarkable history.
It is warmer in Agadir in the winter than it is in Marrakesh, this is why it is a popular winter-sun holiday destination. The highest temperatures occur between June and August.