When Matt Gemmell said he had given up on the Apple Watch and went to the FitBit I realized that battery life was extremely important to me too. I use a Mi Band 2 made by Xiaomi which lasts a month on a charge. They are around $27 on Ali Express and there is a newer model out - the Mi Band 3 which is about the same and says it lasts 20 days on a charge. My Band 2 does heart rate, steps and sleep tracking. And it vibrates when I get a call or text which I really like because I keep my iPhone 7 on silent almost all the time.It has an app for iPhone and Android. It is supposedly waterproof and i have left it on in the shower by mistake with no problems.I found the the rubber wristbands it comes with can drop off unnoticed and I spent about $8 for a Mijobs metal band that has kept my second one safe. Xaiomi makes attractive gadgets so it just doesn’t feel cheap - particularly with the metal band. For me it does all I need and because of the long charging interval does not force me to choose between tracking daytime activities and sleep tracking which distinguishes between deep and light sleep.