Hey, trying to decide on my next bicycle investment.

Amazon has this Garmin vívoactive HR GPS Smart Watch, Regular fit - Black on sale for 140 USD. It has a HR function, and can sync with the Cadence/speed sensors for the bike which is another ~40 extra, will also give elevation etc etc.

On the flip side, the other option is a dedicated bicycle computer like the 520 or 820, which is around 300 with the cadence/speed sensor.

Any opinions on using either? Main goal is to track cycling data, progress etc, eventually training for a century!