In my testing share map is a tiny bit more effective, however I prefer ROW with inactive players as they can come back to the game at any moment.

Not sure on the exact specifics but good ol'randomperson0195 put it well. Also a common mistake that I see is people forget to trade embargo before declaring war. If you trade embargo wait one day then declare war, your global popularity will take less of a hit.

To add on to everyone else's feedback, by having positive relations with player's on the 'Most Feared' list, you also drop your popularity. At the end of the day, if you're down below 40% popularity with the AI, you're probably never going to be back on their good sides within that round. That's why it's important to treat your popularity with delicacy if you anticipate having too many AI neighbors late game. Early game, people like to take those one-city nations. However, everytime you declare war (even with the above mentioned trade embargo), you still take a hit. If you're only getting one city out of a country, is it really worth the penalty? Or should you maybe wait for someone else to take it, watch them become 'Most Feared' and then attack them later on - receiving a popularity boost!

The alternative to maintaining positive relations with AI, is obviously to conquer them all. This can be difficult if you have aggressive or unpredictable human neighbors too close.

Best of luck!

It is important to note that many top-level player don't attack just for the desired resources or because of their war lust, but because they want the +10% morale boost, which increases resource production output and also decreases production time (barely, since 70% morale doesn't do much). It's important to strike a balance between being aggressive, getting the benefit early on, but suffering the drawbacks much later, and being cautious, losing some benefits early game, but later on gaining an advantage over your carefree enemies.