General thread about running with smartwatches.

Why do you run with (or without) a smartwatch? Which model do you have? What functionalities do you use often or are there any that you think are redundant? Did yours ever broke down? Are the sensors accurate?

Currently I do not have any but plan to buy one, budget max 200eu. Both the garmin forerunner 245 or 55 seem like solid choices but I am open to suggestions.