In a given alternate (or the OTL) universe, if the Europe-Mediterranean region is the most advanced in the world, or one of the more advanced regions in the world, then Iberia will colonize America first, excepting Newfoundland and the rest of East Canada, which may be colonized by a nation in Scandinavia or Britain if they get Iceland and Greenland first.
(Because of Iberia's closeness to the New World and winds that go south then southwest and west, as opposed to the Gulf Stream which goes against any ships from France or England trying to get to America.)
The Cadiz area will usually have a big port. (That's another reason for the first one.)
Istanbul/Constantinople/Byzantion will be a big important port. However it will not expand to the other side of the strait, whichever side its on ITTL, unless industrialization starts.
The East Pyrenees are easy to cross. The west Pyrenees, less so. The mid Pyrenees... basically forget it.
The Mediterranean will have a lot more exotic animals if the Roman Empire never forms. For example the North African Elephant.
Arabia must all have the same religion to be united. And to conquer Arabia, you must be a semi-nomadic nation centered in the desert. Preferably an Arab one.
North Africa is fertile in ancient times, but not so much later on.
Before the 20th century, Europe was the most populated place in the world relative to its size.
You can only have a large north-south empire if it's along the coast, like the Inca empire. It's generally easier to expand east or west.
(A river like the Nile works too)
West Africa will usually have a hard time prospering because of malaria and the tsetse fly, among other diseases and pests.
One does not simply invade the Ethiopian highlands (Unless they are Ethiopian).
Ukraine is very fertile, especially the Dnieper River, but it will not get a high population until its inhabitants settle down in cities and farms instead of being migrating steppe nomads.
Mexico has oil.
Pennsylvania, surprisingly, has oil.
Obviously, Texas, Canada, etc. have oil.
Southwestern Britain has a lot of tin.