I own both electronic and mechanical shifting bikes. All that I own are Shimano (except my soon to be built tri bike), but I have also had the opportunity to work on and ride bikes with SRAM eTap as well. While I enjoy always being on the newest and best technology, I find that the decision of whether or not to ride electronic isn’t so simple.
The quality of shifting can be surprisingly similar between the two. I have Ultegra R8000 components on my Domane, and I was really impressed with the shift quality. My previous experience on my own bikes was Ultegra 6700 10-speed on my Tri bike, so this was a big improvement. I think the shifting in the end feels very similar to the Ultegra electronic shifting, and that the real difference is just being able to press a button instead of pushing the whole shifter. The place I have really seen this as a benefit has been with a customer who has wrist and hand problems who benefits from only pushing a button.
While the shift quality is similar, there is a lot less maintenance with electronic shifting. You don’t need to worry about things settling in and cable stretch, and if you’re on hydraulic brakes you really don’t have much to worry about for a while. As a mechanic, I have no fear of adjusting my derailleurs, but it is nice not to have to worry about as much maintenance.
With less maintenance though, you do have to charge batteries. With Shimano, there is one battery, and when it reaches a certain percent remaining it will stop shifting the front derailleur and only shift the rear to conserve power. With eTap, everything is wireless, so you have separate batteries for your derailleurs and shifters. The good news being that if the rear battery dies, you could swap it with the front to hopefully make it home. It would also be easy to carry a spare if needed as well.
The really big advantage of electronic shifting to me came in the form of base bar shifting on a triathlon bike. I raced Ironman Louisville in 2016, and I would have loved this feature back then. With Shimano Di2 the brake levers include shifter buttons or there are additional shift buttons available, and with SRAM eTap you can buy “Blips” or “Clicks” to add buttons wherever you want. The additional buttons are also useful for additional shifting options on road bikes.
Do I have a verdict on what is better? No. I still like my 2013 Felt B16W tri bike with mechanical Ultegra 10-speed just fine, but I am going to electronic on my new triathlon bike for the base bar shifting. I love my Madone with electronic shifting, but the Madone or Emonda I am planning to buy to replace it may be mechanical. For me, I like electronic shifting, but I can’t justify the price on every bike I buy.