Yes, the Garmin units are super reliable, better than phone aps like strava etc.
I have plenty of mates who use strava but generally once they've been at it for a while they get a standalone unit for a variety of reasons, mainly accuracy but also due to mysteriously 'lost rides' which is infuriating. You'll always get discrepancies between different kit, especially elevation so don't get too hung up on that as I think the biggest issue there is the GPS accuracy. I swapped to a wahoo elemnt bolt from a vivoactive watch & a lezyne macro GPS purely due to battery life on long rides, so consider that before you take the plunge on anything.
I personally would recommend all 3 I've used - Garmin, Lezyne & Wahoo - they all do a great job at a range of prices. I bought an ANT/bluetooth chest strap from
Decathlon for £30 and that's been great, not a fan of wrist monitors (my old one was hopeless) and bought speed & cadence sensors.
The latest Lezyne units look to be stunning value.