I have a cheap (£25ish) set off Amazon and its helped me lose about a stone this year, i know that doesn’t sound loads compared to some peoples achievements but for me its made me quite happy.
I link mine to my fitbit account which is very handy because it adjusts my calorie burned figure related to my body composition etc. Using this together with food logging on myfitnesspal (which also links to fitbit, i just use it because the food database is massively larger than fitbits own) makes tracking calories a lot easier to stick to on the long run.
I quite like the history logging feature too with graphs etc.. means i don’t have to go writing anything down in old diaries only to never look at them again.