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 vs 530: Is Now The Time To Upgrade To Touchscreen? - Sportive Cyclist
Garmin Edge 840 Cycling GPS In-Depth Review
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
Which Garmin Edge® is right for you? #2023
Garmin Edge 840 Touchscreen GPS Enabled Cycling Computer 010-02695-00 753759299927
Introduce the rider you are today to the one youll be tomorrow. The Garmin Edge 840 GPS Computer offers targeted adaptive coaching when used with your compatible power meter and heart rate monitor. It helps you manage your efforts by providing power targets throughout a course plus stamina insights so you know how much gas is left in the tank. Get superior accuracy under dense tree cover or the urban canyon thanks to multi-band GNSS technology.
Garmin Edge 840 Solar GPS Computer
Review: Garmin Edge 840 Solar
Garmin Edge 530 Sensor Bundle, Performance GPS Cycling/Bike Computer with Mapping, Dynamic Performance Monitoring and Popularity Routing, Includes Speed and Cadence Sensor and HR Monitor : Electronics
Garmin Edge 840 Cycling GPS In-Depth Review
2023 Garmin Edge 540 vs 840 Comparison