Soldato
The soundcore ones are fairly decent, to be honest, when you're out running and have all the background noise you don't really notice any nuances in the music anyway, it's more just there as background music.
A chest strap would be more accurate than a watch, however this is generally for interval based workouts. A watch can have delays in readings so i'll find i can finish a sprint and it's around 30 seconds later that it shows the increased HR, a chest strap will be more accurate and responsive, but for a base reading a watch is fine and as you say has all the extra benefits that come with a watch.
I have a Garmin Fenix 6X Pro, but obviously there's no need to spend that much! I'm not sure about an Apple Watch being most accurate, i had one prior to this, and would often get different distance readings on the same route, something which doesn't happen with Garmin.
Depending on budget, something like the Garmin Forerunner 245 would be a good option. You can also get a music version so no need to carry a phone at all.
A chest strap would be more accurate than a watch, however this is generally for interval based workouts. A watch can have delays in readings so i'll find i can finish a sprint and it's around 30 seconds later that it shows the increased HR, a chest strap will be more accurate and responsive, but for a base reading a watch is fine and as you say has all the extra benefits that come with a watch.
I have a Garmin Fenix 6X Pro, but obviously there's no need to spend that much! I'm not sure about an Apple Watch being most accurate, i had one prior to this, and would often get different distance readings on the same route, something which doesn't happen with Garmin.
Depending on budget, something like the Garmin Forerunner 245 would be a good option. You can also get a music version so no need to carry a phone at all.