Fitness Tracker.... help!

You can't go past a heart rate monitor with a strap. I used to have a Polar with a heart rate chest strap - It was brilliant for telling me accurate calorie burn, heart rate zones etc though I ended up getting a fitbit flex and sold the polar. The one thing about the polar was it could only tell you calories burned during exercise.. I found the strap uncomfortable while running as it became tighter, otherwise it was great! I have just upgraded on the fitbit flex to the fitbit charge HR to get a more accurate heart rate reading & more accurate calorie burn, minus the uncomfortable chest strap. It just depends what you find comfortable though.

The best thing about the fitbit is that you get insight into your health 24/7.

It really depends. What are you hoping to track with it. Many devices are good at somethings, but bad at others, and no device is great at everything.

What are you hoping to learn/get from it?

If you want to track heart rate, any device will work although the heart rate straps will most likely be most accurate. But with heart rate, it's really only for steady state cardio and not for any other activity.

Fitbits track steps and use fancy algorithms to figure out reasonably accurate estimates of your calories, can track stairs with a fluctuating degree of accuracy, integrate pretty easily with mfp, and have various models at varying price points.

The Bella Leaf does much of the above, without the heart rate and has built in menstrual cycle tracking.

There are many options, but each has it's pros and cons.

Figure out what you want to track and google reviews for devices that interest you. You'll find what you want more effectively that way.

I agree with Bane depends on what you want out of it...

I have a Jawbone...which I love. Mainly due to the silent alarm and it looks like jewellery instead of a cheap plastic watch. I am moving to the Jawbone2 or 3 in a week or two for the added looks and benefits of REM sleep tracking and resting HRM.

it really does depend on what you want. I have the vivosmart and love it because garmin is great for running watches, gps, and other technologies, and it's waterproof. others join the fitbit world. polar is another good one.
trying going to cnet or wareables and look at the comparisons