Garmin
Forerunner 255 Series
Long battery; but wrist HR tracking is inconsistent.

Running these analyses costs money. Buy through my links to help keep lights on! I may get a small commission.
Amazfit trex. I have the trex pro, but the newer 3 and ultra are pretty cool. I think they are all less than 300
I agree I too have an amazfit T-Rex ultra , very good for tracking the trail with GPS system, and good battery, rugged for outdoor activities. This is very good for budget constraints. But if heart rate monitoring is a must then I will not recommend this as it's correct only 60% .
the t rex 3 pro seems good and it has calling functions the torch light seems super useful as well, i am so tempted to upgrade from my already excellent t rex ultra
there's the flashlight that's useful in a pinch, i think it has a mic so u can speak into it, then there's also the titanium used over steel and the sapphire glass thats more hardy i am not too sure on the routes yet but yes i think thats the advantage over it too i am currently using the t rex ultra which is still a champ, but fingers are feeling itchy to get the 3 pro
amazfit T rex ultra Orient Kamasu 2 love these 2 to bits in their respective areas!
Nothing compares to the AWU on an iPhone. You won't find anything close to it, sorry. Not Garmin, not Amazfit, not Coros...If you are happy with the AWU I would just save up for the AWU3 and continue being happy. Now to answer your questions as far as I know, there aren't any native apps on the Amazfit ecosystem as of now (YT Music and of course Apple Music) and the controlling the music from your watch that's playing on your phone can be done but on a basic level. You can reply to messages now but you have to use a mirroring app to do this and well let's just say that you having to share your info with a fourth app to get access to to a third one just sounds complicated and not safe. If you are looking for something like a Smartwatch, get am AWU. If you are looking to put more and more into your fitness and lose on a bunch of smart features but still get a decent watch, then the T-Rex 3 Pro might be worth a shot.
I’ve had the TREX 2 for years, it has been an amazing watch. It tracks fitness excellent, most of my workouts are jump rope, running, and swimming. I think a lot depends on the type of work you do. I am a power lineman, so I needed a rugged watch that could get banged around, be exposed to energized high voltage, and very harsh conditions. The TREX has worked flawlessly through all that. If you’re not going to be beating the hell out of it, the balance 2 may be the more professional looking watch.
Don't rule out Amazfit. I've been running a trex for 3 years now. They compare favorably to Garmin.
Garmin
Forerunner 255 Series
Long battery; but wrist HR tracking is inconsistent.

Garmin
Forerunner 955 Series
Best value, clear MIP screen; limited smartwatch features.

Garmin
Fenix 7 Series
Durable, multi-week battery, flashlight; high price, buggy software.
Garmin
Instinct 2 Series
Rugged, solar multi-week battery; bulky, small screen readability issues.

Garmin
Enduro 3
Multi-week solar battery, lightweight; but bulky form factor.

Ranked #1
Oura - Oura Ring Series

Ranked #1
Apple - Ultra Series

Ranked #1
Garmin - Enduro 3

Ranked #1
Garmin - Fenix 7 Series

Ranked #1
Garmin - Forerunner 255 Series

Ranked #1
Oura - Oura Ring Series