My $0.02: I lost about 60lbs with a Fitbit Charge (original) and kept it off for more than a year with a Blaze. Love the Blaze and have several different bands for it - I can make it match for any occasion. Heart rate tracking matches most gym equipment I've used. I use the app to track intake vs burn and have found real world results be fairly accurate. There's always the debate about which tracker is most accurate for steps but as long as it's close, it doesn't matter much. The point is that the tracker encourages you to be active and the Fitbit products do that very well. Sleep tracking is also helpful. The Blaze lasts about five days on one charge depending on activity level, so you can sleep with it and not worry about charging it every night. I charge mine while in the shower in the morning and that works out pretty well.
The Blaze is 100% not waterproof. Can vouch for that personally. My Charge went into the shower, pools, lakes, and an ocean, and never had an issue. That part of it was nice.