If you're serious about tracking your heart rate during exercise, then you need a chest strap HRM. Wrist mounted optical HRMs have their place in motivating people to exercise more etc, but they aren't very accurate at all. I have a Fitbit Charge HR which I use to track my sleep and daily activity, but I use a Garmin Fenix 2 with a chest strap HRM for my running. The Fitbit's wrist-based optical HRM can often be out by a factor of about 25%.
As far as measuring steps goes, Fitbits also chat shit (as do all the other brands of fitness trackers). For instance, I was credited with 500 steps for doing some typing, 300 for mixing a cake, 50 for driving home from work, 50 for scanning my shopping on a self service till, and 100 for sitting on the sofa stroking the dog for ten minutes. That's 1000 steps in one day that I didn't take but that the Fitbit thinks I did. It is still useful for comparing how much activity you did today as compared with yesterday, and lots of people (my mum is one) find it very motivational to set a goal and achieve it every day, but don't take any figures that come out of it seriously.
For the original poster's purposes, I think a Garmin, Suunto or Tomtom running watch with a proper HRM fits the bill better than a fitness tracker.
