Which fitness tracker is the one I need?

[pastimperfect]

There is a lot of choice and it is leaving me confused.

I would like to buy myself a fitness tracker, but also want to spend my money wisely.

Which would be the best one to get that would monitor steps taken & calories burned?
What is the advantage of knowing your heart rate? Is this option worth paying for?

Any guidance gratefully received

Tracking heart rate means it would be more accurate in estimating calories based on your effort. Trackers without heart rate monitor just guess calories based on your weight and number of steps.
Me, I have a Fitbit Alta. Doesn't do heart rate. I'm really happy with it. The sleep tracking function is rubbish though.