Any recommendations for fitness trackers?

Depends on what type of activities. I like my Fitbit charge HR because I can challenge my friends so we can see who can get more steps throughout the week. I also like how it reads my heart rate and I wear it all day. The polar watches I think are more accurate but they're only for workouts, not an all day activity

I had a Fitbit charge HR and cannot recommend it. I loved it when it worked, but my first one broke in 3 months. Then, I had a second (they replaced the first under the warranty, so that was great), and it lasted 6 months before water got trapped under the screen (from me washing my hands), and then the screen stopped working completely within a couple of weeks. They just didn't hold up well for me. Other people's experiences may be different, of course.