Got any favorites?

Nothing wrong with that. There’s something to be said for going with simplicity. Way easier to fix if something goes wrong. If I was doing some really hardcore touring through remote areas, I would definitely favor friction shifters for this reason.

It’s rechargeable battery powered. The front derailleur takes more power to do its thing, so when power is low, the system automatically drops you into the small chainring and disables the front shifting. The idea is that this will get you home relatively comfortably since you still have the full range of your cassette.

Still…a full charge lasts me many weeks of riding, and I ride quite a lot…about 10-15 hours a week.

Also, I’m describing shimano’s version of electronic shifting, where everything is connected physically via electric cables, so there’s one battery (mine is hidden in the seatpost). Sram’s offering has every component (derailleurs, shifters) communicating wirelessly and every piece has its own battery.

I have it on my road bike, but they also have it for mountain bikes.

In addition to shifting, you can even get electronically actuated dropper seat posts these days :)

Front and rear derailleurs are servo controlled. These connect to a central unit that also has the shifters connected to it. This central unit can communicate with a bike computer (via ant+) to show gearing.

In addition, you can set it up so that when you shift the front derailleur, it automatically moves the rear derailler. You might want to do this in order to keep roughly the same gear ratio when changing chainrings. Or, there is a mode where you just shift up and down, and the system manages the shift for you, shifting either (or both) derailleurs, simulating a 1x drivetrain.

All of the popular group sets have a version of this: shimano, sram, and campagnolo.

It’s very expensive lol

I have electronically actuated (as opposed to cable actuated) gear shifting on my bike. It's becoming way more common these days, though...but still, it's a pretty expensive piece of kit for quite marginal gains.