I used i3wm for many years. It's great. However, at some point I felt fatigued and decided that I didn't
need the additional complexity and manual labor. Sure, I may save a few seconds every day, but I also lose a bunch maintaining my config file and providing basic funcionality that is not out of the box. Nowadays all major desktop environments have great tiling features and extensive keyboard shortcuts -- especially KDE Plasma, which is what I use now.
I recommend a TWM if you have the time and the energy for that, if you want to tinker a lot your environment. It can be pretty cool, but also a drag. There's always some little thing to fix, and basic things are simply not part of the package. So be prepared to write scripts and use third party tools with varying degrees of documentation for many things you take for granted on a desktop environment.
Regarding your other concerns, you can literally change all keybindings on i3wm, so you can make them follow the logic you're already used to. And i3wm is great for working fullscreen as well.
I recommend a TWM if you have the time and the energy for that, if you want to tinker a lot your environment. It can be pretty cool, but also a drag. There's always some little thing to fix, and basic things are simply not part of the package. So be prepared to write scripts and use third party tools with varying degrees of documentation for many things you take for granted on a desktop environment.
Regarding your other concerns, you can literally change all keybindings on i3wm, so you can make them follow the logic you're already used to. And i3wm is great for working fullscreen as well.