An unusual comparison at first glance, but bear with me. Now the 840 has 'all the buttons' it's a relevant question. So here's my answer
Garmin Edge 840, Compact GPS Cycling Computer with Touchscreen and Buttons, Targeted Adaptive Coaching, Advanced Navigation and More : Electronics
IN THE BOX: 1x Edge 840 Solar Cycling Computer, 1x out-front mount, 1x standard mount, 1x tether, 1x USB-C cable 1x Wearable4U E-bank (wa001)
Garmin Edge 840 Solar GPS Cycling Computer, Touchscreen, Button Controls, Advanced Navigation with Wearable4U E-Bank Bundle
What's the difference between the Garmin Edge 1040, 840 and 540 cycling computers? - BikeRadar
Garmin Edge 840 vs 530: Is Now The Time To Upgrade To Touchscreen? - Sportive Cyclist
Garmin Edge 840 Review!
2023 Garmin Edge 540 & Edge 840 Review, ERIK'S Bike, Board & Ski
Garmin Edge 540 & 840 Compared: IN JUST 6 MINUTES!
Garmin announces the Edge 540 & 840 series of cycling computers
Garmin Edge 840 Cycling GPS In-Depth Review