When I was faced with a similar choice I chose a watch and don't regret it. They help to monitor my health, the quality of the GPS signal is at the highest level, plus I can always connect to my phone, even if it isn't near me. When choosing a watch, you should pay attention to your Hobbies. I, for example, do triathlons and chose watches among the best on the market on https://www.bangonbest.com/best-triathlon-watch/. If you don't do sports, you can choose the simplest model without additional features, this will help you save money on unnecessary features. Be sure to pay attention to the quality of the watch, as it's very common to come across fakes.

I had a similar choice to make earlier this year and I didn't want to spend big bucks. I purchased a XOSS G+ computer from Amazon. It does speed, distance, heart rate and various other things. The cadence sensor and heart rate monitor were separate, I think I spent about $85 total for all 3 pieces. I also purchased an extra cadence sensor for my spin bike and use Wahoo for my spin bike workouts. I get cadence and heart rate when using Wahoo for those workouts.

Since I am returning to biking and not in great shape, I appreciate the heart rate alarm on the XOSS. It reminds me to back off a bit when I am working too hard with an audible alarm.

It does have some things that annoy me. I have to power the unit off and then back on after the ride to download the data to my phone. Maybe there is another way but I haven't researched it. The display is in miles but the downloaded data is in Km not miles.

I do link XOSS to Strava so my out of state children and I can share our rides with each other. Strava does convert the data to miles.

I started off with a watch (Samsung Gear 2). Found it to be more trouble than it's worth. Next moved to inexpensive cadence and Heart Rate monitors using apps such as the Wahoo app on my i-phone. Better for sure but not fool proof. Finally I procured Wahoo speed and cadence sensors, a Wahoo optical (arm band) heart rate monitor and a Garmin Edge 530 computer.

My advice: cut to the chase, bite the bullet, spend the money, ride and have fun.