A bit late but still... I run with a smartwatch. I have the basic model of the Garmin instinct 2, which you can get for slightly over 200€ usually. Maybe on sale even cheaper. I am really happy with it. It's durable hast a decent battery life and I like the kinda old school look.

I use it mostly to stay within certain effort levels (heartrate zones) during training. Before getting it I tracked some runs with a chest strap and noted thet I tend to run in very high heartrate zones. The watch helped to control that and get a better feeling for what I am doing. With that knowledge my training became way more effective and fun.

And of course to track my mileage in general and during long 'free' runs.