I prefer Peace but war is OP, so I don't really think Peace vs War works, at least not in a "which one is better" scenario. Peace isn't as unviable as Tall, it's a perfectly viable playstyle but still, you can't really discuss pros and cons since War will win every time, it's just OP. If you're the kind of player that want to always take the optimal path or at least something close to it, your only option is war, you can't ignore how good it's. If you're the kind of player that like to set a specific way to play and just go for it, regardless of how optimal it is, then Peace is just as good as War. You gonna win just as easy through Peace but War will do it faster and better.
I like to plan, build and play the diplomatic game. I would rather have my units doing "nothing" than have to move them every turn, to conquer yet another city I will have to manage. It's not like I need more cities to win, so I can't really see keeping my units idle as a waste, it's not a waste if I don't need it in the first place. I'm not trying to set any record on fastest Civ VI victory after all, I'm trying to have fun. I like to play War from time to time but for me, Peace is where the fun is.
I think Firaxis wasted an opportunity on loyalty/era, would be interesting if it worked as a representation of how hard it's to keep a huge Empire together. I been playing R&F since launch, I still didn't get a Dark Age since I refuse to hurt myself on purpose to do it. I'm going for war in my recent match, I'm on yet another Golden Age streak. You just can't get it naturally and it's even more unlikely that you will get one if you choose war when it should be the opposite. In a domination match, it should be extremely likely that you will get at least one Dark Age in late game, almost impossible to avoid.Instead you get one Golden Age after the other. They need to increase the penalty per city in the era points system and increase the penalty per golden age. It would also be interesting to get another penalty on top of the occupation penalty, one that stick around even after peace and maybe fade with time, to represent the fact that the city didn't join you, it was conquered. They are now part of your Empire but it will take time for them to be mixed into your population and truly become a part of it. A French city still French after conquered, that should be represented somehow.